Using dirt/flour to detect invisible creatures is a bad idea: 

Quote from nadiahaik78 >>

So I’m playing a new D&D session and one of my friends i play with came up with some really interesting little tricks that anyone can do in game for example:

One player has a really shiny cane, he looks in the reflection of it when he meets new people to see if he can see them, if he can’t he knows they’re a vampire (because there’s a lot of them in this campaign)

 Well, that's going to cause issues with any attempts at diplomacy following such a wierd first impressions.

Wow, that guy is obnoxious.

Flour isn't going to totally overcome invisibility. As in there's still an Invisible condition. They're not going to be seen, there's no getting around that, but they might no longer be heavily obscured. You can see the void where they would be, so if they were relying on their invisibility to stay hidden that's gone. The only real issue is adjudicating how big an area one full sack of flour is going to fill.

The shiny-cane bit is actually clever.  That's a fun little trick if reflectionless vampires are a significant problem in your game.

Don't really have a formal collection of D&D lifehacks, but I'm gonna remember that cane bit.

I'd prefer to use a shiny paladin for reflection checks. Much more useful when you actually find that vampire.

Exactly. Interfering player is looking out for his own skin - not that all their opponents should know so much about them to know to all carry flour to stop an invisible player, or that all their opponents from then on even have flour in their kit... so long as they don't brag about how they defeated something, when back at the pub later...

While the video provides a reason not to use flour for the players, even in RAW it should prove less useful than presumed.

Invisibility does not state any restrictions under which you are not invisible. You can cast the spell underwater, in fog, rain, a sandstorm, and you will remain invisible. Invisibility is an illusion, so I am assuming it will compensate appropriately for the atmospheric conditions.

The condition invisible allows detection by sound, or by the tracks the creature leaves. Being coated in flour does not seem to be tracks in my opinion, neither would being in a dust cloud. Leaving tracks on a flour coated floor does count, as would on a wet floor, or a wet creature on a dry floor. However, all those still mean that the creature itself is unseen, which grants them advantage on attack rolls, and disadvantage on attack rolls against them.

In combat, I leave a marker on the grid, showing where the creature was last heard, unless the creature makes a stealth roll to hide. Only a successfully hiding creature gets their token removed from the map. I would grant disadvantage on the stealth roll to hide, if the creature will leave tracks, however.

Complaining about invisibility isn't the purpose of the thread, folks.  Yes, DMs hate the "I throw flour/dirt/sand/ball bearings/whatever" business.  Players hate when DMs make an entire encounter around a single invisible creature they don't allow the players to detect through any means short of "WHELP guess you should've read my mind and prepared See Invisibility today, but because you didn't this invisible critter gets to take free shots at you until I get bored of it."  That is a problem that happens for many reasons, and most of them are not the players' fault.

Nevertheless.  D&D lifehacks, not Invisibility complaints.

Okay, getting back to the idea of sharing some tips and tricks... buy some chalk! The most common use I've seen mentioned is marking the walls in a labyrinthine dungeon to keep track of where you've been. You can also use it to leave messages, or even to set false hints to confuse people following you.

Don't forget your ability to Ready actions. If you have nothing you can do in a round, ready an action so at the very least you can be ready to do something. Fighting a flying enemy and don't have any ranged weaponry? Ready an attack so you can strike back when the enemy comes into range... or, if you've got the strength, ready a grapple so you can hold them in place so they stay in range. Alternatively, don't forget the Dodge action... If you're surrounded by enemies, sometimes it's worth missing a round of dealing damage to dodge and give yourself that extra bit of defense to stay up while your allies catch up.

Look for ways to use your tool proficiencies. if you're proficient in smith's tools, unless your DM gives you a lot of downtime, you're not going to get many chances to actually craft weapons and armor. But your proficiency still gives you knowledge specifically related to your chosen craft. Found some ancient armor and you want to know where it came from, but you're not proficient in History? Your DM might let you roll using your Smith's Proficiency to recall information from your training to realize it's a Dwarven Chest Piece and it might have value to a specific clan.

Okay, so I went through some of my old books and found something in 3.5's Dungeonscape. I don't know if this is the first appearance of the technique (I started playing in 3.0), but it's an appearance.

Flour Pouch: This deceptively simple burlap satchel of flour is tied loosely on purpose. While it could be used to bake a loaf of bread on a particularly long expedition, its true purpose is to locate invisible opponents. You can attempt to strike an invisible opponent with a fl our pouch as a touch attack. You still must pinpoint the target or choose a space to attack into, and the normal miss chance for total concealment applies. If you hit the target, the pouch bursts open, spilling white flour over a portion of the invisible creature. You can also throw a flour pouch as a splash weapon; any invisible creature standing in the space struck is covered in flour, as are all other creatures within 5 feet.

Coating an invisible creature in flour lets you keep track of its position and reduces the miss chance to 20% (instead of the normal 50% for total concealment). While an invisible creature is coated in flour, its bonus on Hide checks is reduced to +10 if the creature is moving, or to +20 if it is not moving (PH 76). If the creature moves through water, is subjected to a gust of wind, or spends a full-round action brushing the flour off, all the flour is removed from its body.

 It only cost 1 silver and had no weight listed. But, yeah, I think treating the target as lightly obscured as opposed to heavily obscured is the right way to go. You can't see them, they're still invisible, after all, but they can't hide unless they can also hide when lightly obscured. I'd be looking at the wood elf, but Mask of the Wild only works in "natural phenomena." I don't think this counts. And, with that low a return, I don't think it's worth it.

Let's give it 20 feet, like the vial of acid and alchemist's fire. Not sure about the splash, though. The other items don't.

Always keep a potion of gaseous form with you if you can. If you're ever swallowed by a monster, you can easily just pull out that potion, pour it into the creature's mouth, and escape. 

Quote from Third_Sundering >>

Always keep a potion of gaseous form with you if you can. If you're ever swallowed by a monster, you can easily just pull out that potion, pour it into the creature's mouth, and escape.

Oh that's very clever, I like that.

Good point, TransmorpherDDS! We should be discussing tips, not someone else's video.

Magic items are cool and all, but don't be afraid to spend your gold on more mundane upgrades. This means watching weight and lightening your character's load. I had a player who made a cleric with 8 Strength. They stuck him in scale armor with an explorer's pack (class) and the monster hunter's pack (background). He was so overladen with gear he couldn't actually move. We needed to reassign ability scores and bring that Strength up to 12 just so he could walk with all that in tow. He wasn't happy, but it was a learning experience. The less your standard equipment weighs, the more stuff you can carry. This included loot, too.

Torches are cheap but heavy. Invest in a lantern and some oil to lighten your load. For just six hours of light, that's half the weight. For equal weight, it's 48 hours of light instead of 10. Oh, and a hooded lantern increases the radius of light provided by 50%. Darkvision helps in dim light, but you're barely better than blind in darkness. You can't see in color, and you'll have disadvantage on visual perception checks. Don't skimp on the light.

Silk rope weighs half as much as hemp. Assuming you can't find potable water, it takes two full waterskins to get you through a day in the wilderness. Don't underestimate the usefulness of silvered or adamantine weapons.

You don't start with a tankard, so if you want one you'll have to buy one. Actually, D&D Beyond doesn't include any containers for your characters. If you start with a longbow and 20 arrows, or a light crossbow and 20 bolts, it doesn't assume a quiver or case. To be fair, starting equipment packages don't mention these by name. But they shouldn't have to. And the Character Builder does it give you a pouch for your starting gold, and every background which includes gold pieces explicitly calls for one. Even if you don't buy a tankard, add the containers.

And do not underestimate the usefulness of mounts and pack animals.

Quote from Jounichi1983 >>

And do not underestimate the usefulness of mounts and pack animals.

This, big time. Mounted combat is a tiny bit clunky, but there are still benefits and it and anyone can take advantage of it! If you're really hard up for money, you can get a mule for only 8gp. Ahh, I just noticed it's a mule is Medium. Well, that still works for small characters. I had an archer Battlemaster who lost his first mount and ended up buying a mule to replace it, lucky I was a Halfling.

Oh, and going back to my comment about flying enemies or enemies that are generally out of range...

I feel like some new players don't know this... Ranged weapons key off of DEX, so if you're a STR-based fighter, you might not see much value in carrying a Ranged Weapon. However, some new players don't realize that weapons with the Thrown property key off of STR. Your best bet is to carry Javelins, since they have solid range and are fairly inexpensive. They're kind of clunky to carry around, so if you're looking for something smaller a handaxe is probably your best bet, since it still deals d6 damage, although they each cost a hell of a lot more than other options. If cost is a factor, just grab a bunch of darts... it's the only weapon I can think of that's priced in copper.

That potion of gaseous form thing is brilliant.  That's an expensive get-out-of-jail card, but man.  What a way to flip the bird finger at a Purple Worm.

Quote from Third_Sundering >>

Always keep a potion of gaseous form with you if you can. If you're ever swallowed by a monster, you can easily just pull out that potion, pour it into the creature's mouth, and escape. 

 Or you can drink it yourself and be burped to freedom! (or the other exit...)

Quote from HailRobonia >>

Quote from Third_Sundering >>

Always keep a potion of gaseous form with you if you can. If you're ever swallowed by a monster, you can easily just pull out that potion, pour it into the creature's mouth, and escape. 

 Or you can drink it yourself and be burped to freedom! (or the other exit...)

 If you can get your hands on one, sure. It's bad to assume access to specific magic items as a general rule. Even if a module prescribes one, the DM can change it.

Could always try and craft it.  And if you do have a Potion of Gaseous Form, now you know a cool alternative use for it.

I'd rather lose a pricey magic potion than an entire character, and I'm pretty sure most of us would agree.