I just try to tell noobs to 1. host their own game/join "noobs only" games, and 2. read the forums a bit. Granted, not many people listen, but on occasion someone will say "thanks" and then go do it.
The biggest issue is that in Demigod one bad person can very very easily lose the game for a number of competent (even superior) teammates. So it really is imperative to prevent someone who doesn't have any idea what they're doing from joining a game where everyone else is a solid player.
Not this thread will ever be read by any of the "real" noobs, so I doubt it will do much of anything.
Not even that, but bad builds on your side will get good players killed when they are the tanks and get focus fired by good builds.
The most infuriating things I can think of are.
1) I lock a flag we just took from a DG in the lane so we can push the flag in the other lane. Then squishy decides this is the time to push the tower. Do I leave him to die? No, but I just wasted a lock.
2) DGs who don't stay focused on the hurt or weak DGs. This is especially bad when you have 3+ more on a team. You get the "OMG Don't die!" blame, because they just don't understand they got you killed by spreading dammage out across all the DGs as they shuffle around letting them all stay in play to continue doing focused damage.
I see this so often.... Grrrrrr!
3) Mirror DGs when you have the noticeably less effective mirror. Hey look, Shadow swap triple gank.... shadow swap triple gank... dear DA on our team, please continue your swapless speed build because we are going to win this way!
4) Expectation of shields/heal- You should be able to play and not get in trouble without these things if you don't have them. These things are a courtesy, or necessity only when the other team used a good tactic or you did something productive. If you run past the flag we don't own and get TP gank inbound, I really need to let you die as you run away to base so you learn.
5) Losing ground in a 2on1 when your teammates don't counter push. Hey yeah, I let the tower die, but it is 2on1 this side... WTF, you have 2on1 on the other side, why is that tower still there?
Basically, it all boils down to getting someone on your team killed and then blaming them since they are the ones who died.
When a team mate dies, watch the damn replay and look at not only what he did, but what the enemy did, and what you were doing at the time. Sometimes there is nothing you could do (or should do 
), other times you get an idea on improving your game and learning. I do this after every close game or loss.
