In general, when your opponent plays moves like e3, Nc3, etc. he/she is not looking to control the centre. By fighting back with moves like .. c5, .. Nc6, .. Nf6 before you decide where your bishops go should be preferred. Your .. Bf5 was not necessarily bad, but 5. .. e4 wasn't necessary at all. Keep developing! He was worried about you exchanging, but keep the tension! If he wants to exchange, let him. Keep developing! After 8. f4, play 8. .. exf4 and the tactics should just fly. Look at more tactics programs (or the great Chess.com tactics trainer) to get comfortable in when you should attack and when you should trade off.
Fail Streak Game #9

Here's some free advice. With a Queen Pawn opening, you usually want to push your pawn to c5, so developing Nc6 before c5 is not good. Nf6 would be better.
Also, 6. ... e4 blocked your Bishop.

it's not "maybe f5 would have been better", it's "f5 was obviously better".
this should have been an easily won game. I'm going to be nicer with my analysis than game 10 because i'm seeing a clear theme among all of your games. here's the big one.
DOUBLE CHECK YOUR MOVES.
before you even think of moving, look at ALL of your pieces. are they all defended? is anything under attack? if so, what needs to be done?
so, focus on these three key aspects of your game.
1. Castle early. you did this, but at the cost of your bishop.
2. Develop your pieces. one piece at a time. queen LAST, usually.
3. Control the center. this isn't a problem for you. you're making *mostly* smart moves about this. keep up the good work.
ksadler's right about en passant: exf4 and white's in even more trouble.

General Rules man, just stick with them. Learning not to make bad moves comes the more you play. If you have time on the clock don't rush, you might want to avoid blitz games for a while. Also something important is don't get frustrated, that is usually where bad moves come in.
Do as the posters said above me but also when an opponent makes a move stop and ask yourself 'what is their threat?' This might prevent you from losing your bishop when you saw him start a pawn attack with his kingside pawns.
This is game 9 [of 10] of my fail streak.
Feel free to help my analysis.