During last nights practice we starting talking about champions we hate to lane against. We talked about how to deal with them and how to handle times when we get behind. Here is what came out of our discussions, again this is the theory, we still need to test this out more:
1) Unless you are the carry, your build is based on how the game is going for you.
2) If you are ahead then buy some damage items, if you are behind then get some defense based on the kind of damage you are dying to (Magic/Physical)
3) Once you have 200 points in whatever defense you are building, don't get anymore, buy health instead. Each point in health will be worth more than a defense point. Also if you are getting mixed damage health will benefit both.

We had a game where enemy top lane got fed early. It was Wukong and he was three levels above everyone on our team. We did not respect the level difference and hey pretty much one-two shot everyone that went against him. We did not go in as a team and we continued to feed him. It got pretty bad. We were able to kill him a few times with magic damage once we were in a good position, unfortunately he always managed to get into our back-line and kill all our damage dealers. We did lose, but we also learned.

When a lane is having a bad time due to a matchup problem, or the jungler is camping a lane since its squishy or easy to kill it needs to be communicated to the team. You have two options:
1) Send help. Either shift a lane to collapse, send the jungler, anyone who has teleport. Do it in significant numbers, ensure the kill.
2) This is the chance for others to push the advantage. Send the jungler to a weaker lane and get objectives, if you can get an inhibitor it can release a great deal of pressure on your team keeping the enemy busy.
3) Keep feeding and hope they end the game early so you can try again.

Our coach gave us some great advice (Oh, yea get a coach. Someone who can be objective) Dying is more of a deficit than getting a kill. If you are getting dived on just let the tower go, don't give them the kill.