One of my friends who I have played in many games with in the past - both games that he has run and games that he’s played along with me, run by someone else, recently started up a new campaign for the purpose of introducing two new people to D&D. Neither of these guys have ever played any tabletop role play before at all.  Our group has one other veteran player who I’ve also played many games with.  

We’re two sessions in, and so far everyone is having fun, which is great!  But I’m noticing that the newbs are still very much thinking in video game mode.  What I mean by that is, they’re operating under the assumption that they can rob and murder and intimidate and loot as much as they want, and the environment and characters around them won’t react much beyond minor variations in tone and so forth.  The most stand out example: last session, my character almost died (at 0hp, sitting on 2 failed death saving throws), and the newb paladin decided to take the time to loot the body of the dead boss before coming to help the newb warlock save my life (I got better).  I’m not too worried; I knew what I was getting into when I signed on for an introductory campaign for new players, and I trust my DM to teach them that, y’know, actions have consequences, and so forth.  (Plus, if I die, i’ve got s backup character ready to go that I am very excited about)

I’m just wondering, does anyone have any thoughts on if there is a way for me as a player can help teach these new guys how to play in a way that’s a little less video game murder hobo-y, and a little more collaborative and cooperative, without making them feel like I’m picking on them?  The last thing I want to do is sour their first experience with D&D, and turn them off of the game as a whole.  I want to be helpful, but I don’t want to be a nag.  Or am I just worrying too much, and I should just relax and enjoy the game, and assume they’re doing the same, and trust that they’ll say something if not?  

Actually, a better, more general question would be: does anybody have general tips for playing (as a player, not a DM) with new players?  I haven’t played with newbs since I was one myself.

Shock and Awe. It might sound dumb but do something out of character for you personally but that your dnd character might do. Like try and seduce someone, use a spell in a jokey manner, make breakfast (heard podcast that i can't find or i would link it, they gather ingredients for breakfast). Most new players think like video game rules, so if you start doing things outside of those rules people start to see the world differently. Also talk to your DM about it, if you help someone they would normally attack and that NPC helps you back. they might start to see NPCs as more than just fodder. 

For me i dislike when new players play spell casters then use every spell slot on every fight and want to rest every 5 min. Oh the town that is on fire, is about 10 mins away but you want to spend the next 8 hours sleeping!? the town will be gone or the fire will be out by the time we get there! 

Something that ends up happening to me every single time I play with new people..I end up the de facto leader. I generally don't mind as it allows me to mitigate a lot of what new players do, I can point the players in directions, I can steer the game so that it adheres to whatever the DM is trying to do. I also spend a lot of time teaching players how to play their characters, in a mechanical sense, so I'm doing all of this helpful stuff as a player. Anything and everything to make the game run smooth and get the new players more familiar with the mechanics of the game.

As a character....I'm going to respond in whatever fashion most resembles their personality and ideals. My ranger/rogue met his party for the first time and based on how my players spoke up and described things, I labeled them, one got called a liar, and I stuck to it for many, many sessions. One of my other characters abhorred killing, he would do whatever it took to subdue a creature/person, I was a royal pain in the rear to my players because of this...a wizard pacifist...just let that roll around in your head. I am now playing a Dwarven Barbarian, entertainer/gladiator, think the dwarven version of WWE. You start murder-hoboing around him...he'll find the local authorities and turn them in...

You can teach best by example in my opinion, rather than telling them to stop doing what they want in a game that says do what you want.

My first thought was that maybe your character has caught on that they (their characters) are not team players, could go one of two ways with this. If your character is the good type, then maybe he begins having "visions" granted to him by his patron that says when they try to kill someone, or suggest it, that your patron has seen if they do that certain doom will befall them. You would of course be making this up, but your character might be able to steer them inadvertently towards the better path. 

If you wanted to go the opposite direction, similar to Halfling's idea above, have your Warlock catch on and decide that these two fools are ripe for harvesting in the name of your patron (this assumes you don't have a celestial pact or something), so you begin egging them on, pushing them to be more murder hobo so that they eventually take the life of an innocent and stain their soul for your dark lord. The hope here would be that while your character is doing that the others catch on that doing those sorts of things are evil and instead will go the opposite way. (This one may end with them attempting to end your life, so be ready with that second character)

First off, Just talk to them outside of the game, and explain that it is not a video game. Explaining "in game," may be lost on them. 
Use your game situations to explain/show a "real life" experience.  Using your above Ex. You got just go to a huge bar fight. I am knocked out on the ground bleeding... would your really go over and take the other person's wallet before checking on your friends?
However, being a murderhobo is fun and is the easiest. In general they do not have to take things too seriously, because D&D is a game. The point of a game is to not take things serious. So the idea that there are "real" consequences is typically lost on players new to the game. I would also talk to your DM how he/she wants to handle the situation and how you can help. That you are willing to "sacrifice" something to help the new players learn something; could be situation like having them get arrested or the paladin loses powers as a warning for what they have done. But this should be simple to overcome. A few gold pieces or a trip to a temple to the paladins God. A small way to show, "Oh. I can do whatever I want, but there are consequences." Sometimes the safety of the gaming table gets in the way of experiencing the game on level a that is deeper.

If you want to stay in game, have your druid ask them philosophical moral questions. Like what is good? What is evil?

As far as, general tips for new players:
I use a lot of theater of the mind with new players. Maps and scale and movement is an extra layer they don't need on top of all the other "new experiences" and rules. Speaking of rules... I take the rule books away from them. When they ask if they can do something. I say, "I don't know can you? Only way to find out is to try it. Would you like to try?" In my experience, it gets the players way from explicit rulings, and lets the narrative take over.

When I describe spell effects, I talk directly to the new player. Even if it is not their spell. A new player has never seen a cantrip, much less a fireball. Making cantrip seem mystical and wondrous means that the high level stuff is going blow their mind. 

I let my new players have a lot of control over stuff. I will describe a tavern or inn, after I am done I ask them what do you see or hear or smell in your mind's eye. It can be anything (NPCs in the common room, decorations, conversations, etc. I find that it is never anything game braking), I add it the game. Usually expanding on it as I turn and talk to the rest of the players. Same with most locations. I take notes to see what the player is adding to my game and try to use those details more often. It also lets them feel they are part of the story creation. That it is not just my game, it is our story.
I will add personal descriptions to scenes. Like moving through the sewers. I will describe it; but then add, "You are looking down watching your footing on the wet walkway. Your face brushes up against something slimy hanging down from the ceiling and it leaves a wet streak across you face and hair." Or, "You feel your boots fill up with water. The wet doesn't bother you, but the something squishing between your toes does..." help make the experiences a little more personal.

I also tend to fudge the game in favor of new players. Mooks and Lackeys don't do as much damage so they say in the fight longer, dramatic misses, DC for success on a skill check is a little bit lower. But also, the bad guy, is really bad to them. 
Ex. in my latest game, the new player is a bounty hunter. Sees the bad guy in the inn. He gets up and leaves, she chases after. She slips past the lackeys but he rest of the party doesn't. Minor chase scene. She fails a roll bad. Bad guy attacks her from the shadows with surprise. I describe is cold clammy hands, the hot breath in their ear as he is whispering to them. They can smell his rotting breath. Bad guy wins initiative, I fudge the damage to just enough to put them under but not kill them outright. As he slowly lowers the PC to the ground. As the vision fades to black the PC can see him standing over them, head cocked to the side watching them die. They can feel the cloths getting wet and the wet going from a hot liquid to cooling. Fade to Black. 
Now it is personal for the player to get this guy. It gave the new player an experience that blurred the line between game, and something that happened at the "safety" of the gaming table. When they finally meet up with this bad guy in the final fight, I will fudge the hit points, to make the final blow land on the new player.

Last thing I do, I try to remember all the crazy cool/scary, stuff that is memorable to me as a player that other DMs have done. I make sure to do those things for my players. One that stands out, First time I ever played DnD. It was 1st AD&D, I was eight and my older brother was running it for his annoying little brother. I am investigating a ruined moathouse in the swamps. My elf is eaten by a giant frog. I died because that is what older brothers do, but it was a memory that is very real for me as a player. I am going to use giant frogs this week in my game on the halfling and the new player that is an elf. I doubt I will kill them (fudging the rules), but it will be fun and memorable.

Good luck with the new players. Remember the goal is fun. So don't get too hung up one them being murderhobos just yet. Eventually, you can show them through your game play something else and hopefully they will follow you.