preparing for my rival

I currently have a rival who is about as good as me if not better. I have a few problems I have to fix if I want to defeat him though, he is a really aggressive player and loves to play white so first of i need to find the best way to beat him as black, also I'm a fairly good player but i sometimes make moves to fast without calculating and right after that move i see were i went wrong. plz help.

Bacon often posts a list of useful tips.

For example the first post here:

https://www.chess.com/forum/view/general/i-need-to-be-better-i-need-a-book

 yes cellomaster8, I'm just quick to think and sometimes it costs me the game. I need help not your passive aggressive comments.

First piece of advice...STOP with using terms like "aggressive" The only style at your level is "blundering"  Now to answer your question:

Opening Principles:

1. Control the center squares – d4-e4-d5-e5
2. Develop your minor pieces toward the center – piece activity is the key
3. Castle
4. Connect your rooks

Tactics...tactics...tactics...

The objective of development is about improving the value of your pieces by increasing the importance of their roles. Well-developed pieces have more fire-power than undeveloped pieces and they do more in helping you gain control.

Now we will look at 5 practical things you can do to help you achieve your development objective.

They are:

1. Give priority to your least active pieces.

• Which piece needs to be developed (which piece is the least active)
• Where should it go (where can its role be maximized)

2. Exchange your least active pieces for your opponent’s active pieces.
3. Restrict the development of your opponent’s pieces.
4. Neutralize your opponent’s best piece.
5. Secure strong squares for your pieces.

Don’t help your opponent develop.

There are 2 common mistakes whereby you will simply be helping your opponent to develop:

1. Making a weak threat that can easily be blocked
2. Making an exchange that helps your opponent to develop a piece

Pre Move Checklist:

1. Make sure all your pieces are safe.
2. Look for forcing moves: Checks, captures, threats. You want to look at ALL forcing moves (even the bad ones) as this will force you look at, and see the entire board.
3. If there are no forcing moves, you then want to remove any of your opponent’s pieces from your side of the board.
4. If your opponent doesn’t have any of his pieces on your side of the board, then you want to improve the position of your least active piece.
5. After each move by your opponent, ask yourself: "What is my opponent trying to do?"

why should i stop using the term aggressive?

1. It doesn't apply.

2. It will be used incorrectly.

3. It does nothing for your improvement.

4. At your level, the only style is blundering.

yeah but sub 1200 just suck at chess

 Really I never said i wasn't taking his advice.

What you will lose is your love and enjoyment of the game.

I even took the time to expand on my "Opening Principles" cheat sheet....and right now...<sniff> Im not feeling appreciated...

       I appreciate your advice the only problem is Shock_Me is mocking my intelligence.

As long as you continue to ask the wrong questions, you're going to get frustrated.  You're trying to define "aggressive" when you aren't even using it correctly.  Your other post is asking "How to play the Sicilian" when you haven't mastered the basics yet.  I'm not trying to tell you what to do, i'm simply offering advice you need.  You will get plenty of people that will give you the advice you want.  

Guaranteed...at some point, your going to get a reply from someone rated 800 telling you to play the Sicilian Accelerated Dragon (Because its aggressive)

He is telling you the same thing i have said, just in a different way.  I get accused of being "mean" at times because im blunt.  Thats all shock_me is doing...being blunt.