Hi everyone!
I'm a middle-aged guy who hasn't played D&D since the late 80's or so, meaning my functional knowledge of the game is almost nil. My nephews want to play, and I figured that the Lost Mines of Phandelver from the starter set would be a good way to get their feet wet. Our play time is limited, looking at probably only a couple of hours a week. What do I need to do to prepare? We have dice, and the boys have made their characters.  Should I read the whole adventure before we get started? Are there any specific things I should have on hand? Do I need to buy the DM Guide and the PHB and all that, or is the info in the adventure enough for this first campaign?

Thanks so much for any feedback. I'm really excited that I get to be part of passing this game on to the next generation of players!

Nate

With the starter set, you have enough material on the rules to run that adventure. I would advice to give a look at the Combat rules and the Hiding rules beforehand. Those are the more tricky part. Once you get that, run the adventure and you'll learn most of things on the way.

Thanks filcat, I appreciate the help.  I like the first rule in the "Rules to Game By" section of the adventure, "When in doubt, make it up!"  I have a feeling I'll be making frequent use of that one ;)

On a similar note, this adventure is for 4-5 PCs. I've got two, a Rogue and a Wizard. Any tips on keeping the encounters fun?  There's no tank or healer to help with damage. I'd have them create different characters, except they are SUPER excited about the ones they have. I don't want to start off their experience by asking them to give that up and play a character they don't really want to play. I've been considering using the dwarf cleric that comes with the starter set as an NPC that will accompany them throughout. Am I asking for trouble here? Is it foolish to try to run a character and DM?

In that case, I would give the players (in your case the nephews) control over one or two NPCs like: Acolyte, Guard or Scout. Altough they are not playable characters, they make number in the party, at least for earlier levels.

Oh, that's an interesting idea, especially at the start.  Although, it doesn't seem like those NPCs would be much help when the PCs are, say, level 4 and going against monsters with a higher CR. For example, the Flameskull could wipe out one of those guys with one hit of Fire Ray.  Would you recommend just coming up with ways to restock the NPCs when they bite the dust? Or would the two PCs be able to more or less hold their own once they get higher in level?  I like your idea since it takes the pressure of running a character off of me, but I'm worried that once those NPCs are gone they'll have a hard time just surviving even simple encounters. I suppose I could try to rebalance encounters by reducing the # of monsters or something too.

I strongly recommend reading the Sly Flourish series on Phandelver. Mike Shea does a good job taking you through the module from the DM's perspective and offering a lot of useful information. This will help you become a better DM for the module fast, and improve what you present to your nephews.

I'd also use this Encounter Difficulty Calculator to figure out how to tone down the encounters. Phandelver is written with 4 player characters in mind. You can plug in the encounter information on the website to get an idea of how two characters will fare vs. it and then start scaling it down to the difficulty you want (remove monsters, etc.). Also, as they are a Rogue and Wizard, I'd suggest giving them each a Potion of Healing at the start of the game. 

While healing and the "We must always have a cleric!" mantra are no longer as important in 5e D&D as it was in the 80s, this will help accident proof your nephews while you learn to balance encounters and they get used to the game. A little foam padding on the safety rails won't ruin the game at the start and will increase their fun.

I envy you, watching new players learn the game always excites me!

Thanks! I definitely have the mindset of "This group needs a healer!"  I'll definitely take a look at those resources. I've been looking at a lot of things like that to try to help me get my head around DMing.

After they rolled up their characters and finished filling in their sheets, they wanted to have some fun with them. I grabbed a small, one-level dungeon online and stocked it with a few goblins and kobolds for them to thwack. They had a good time, but I also got to see a little bit of the issues of running with such a small party. The Wizard's HP is 7 and the Rogue's is 9, so it only takes a couple shots to bring them to zero. I found that as long as they rolled well, they had enough damage output to handle 4 or so easy creatures. Once the dice went cold, everything went downhill fast. With two finesse/ranged PCs, things got messy if the creatures got close, especially for the Wizard. I did have them find a couple healing potions in the dungeon, and they are also now acquainted with death saving throws.

I gave them surprise on most encounters, thinking that would allow them to soften the monsters up before things got up-close-and-personal. That was true, but it also got a little bit stale, and they just assumed they would be able to surprise anyone and get that bonus attack round every time. These are the kinds of things I want to figure out.I want it to be a challenge, because I think that's one of the things that makes it fun, but I also don't want them to rage quit because they get knocked unconscious every encounter.

I'm really enjoying the content on these forums, as well as a handful of subs on reddit. This stuff is really helpful, and it's great to have a place to hash out some of these things.

I would say if you have free time read the entire adventure before running it. You don't actually have to prepare later parts, but being familiar with them can be helpful.