PH Customz

Ok I use Krylon Fusion paint if your fenders have scratches you want to remove them with some sand paper. To begin, I first used a course sandpaper of 60 grit. Many other people started with 100 grit, but I like to use 60 to make sure that all of the dings and texture come out. This is the easiest time to remove imperfections, so make sure you spend time to get everything else. Once you are satisfied, sand the area with 100 grit, then 150, 220 and 320. At this point, the surface should be smooth, with no major scratches.
 Cleaning
This step is very important. In a tub or whatever, clean the pieces thoroughly with soap and water. Make sure to get into the corners and places where dust could hide. Dry the pieces, then clean them with the rubbing alcohol and allow them to dry. This step will ensure that the primer/paint sticks to the pieces.
 Priming
If you would like to keep the texture, you can use a regular sandable primer. If you are going for the glossy look, you will use a high build primer. It will fill in any scratches and imperfections, thus resulting in a smooth finish.

When priming, and painting for that matter, they key is light coats. Many light coats will allow the paint/primer to build up, and will not cause drips or runs. This is what you want to do. First, cover the area where you will be painting with newspaper or plastic to protect things from over spray. To begin priming, hold the can approximately 8 to 10 inches away from the piece and using smooth motions, lightly spray the piece. Do not worry if it is not completely covered, because you will be applying many more coats. Let the piece sit 10-15 minutes, until it is dry to the touch, and add another coat. Do this for 2-3 coats, or until the piece is covered.

Let the piece dry, and with a piece of 320 sandpaper, lightly sand the primer to get out any imperfections. Clean the piece like shown in section 4. Now prime the piece a few more times, sanding with 600-800 grit between coats of sanding. I usually go a little heavier with these coats, going with medium coats instead of light ones. This will help fill in any scratches more. Try not to go so heavy that you will cause drips, but if you do you will be able to sand them out. When you are done, the piece should be very smooth, and you should not be able to see any imperfections. Anything that you can see now, you will most likely see in the finished product. Go back and either sand or prime to get rid of these imperfections before you continue.
 Painting
Now you should have a piece that has no imperfections, and is ready for paint. If not, go back and fix these imperfections. It should also be cleaned. When you are ready, spray a light coat of paint just like you did with the primer. You will build the paint up with several coats, just like you did with the primer. Allow time for the paint to dry, and spray several coats.

After 3-5 light coats, the surface should be pretty uniform. At this point, sand with some 800-1000 grit paper. Clean the surface, and spray another 3-5 coats. These coats can be medium, but like with the primer, don't go so heavy as to cause drips. If they occur, simply sand them out. You can use 800 grit sandpaper, and if it doesn't get them out, you can drop down to 600 grit. To test that the drip is removed, close your eyes and feel the area. You should not be able to tell where it was.

The next step is color-coat sanding. You will only want to go onto this step if you are using a flat paint, and are looking for a glossy look.
Color-Coat Sanding
This is the step where you will really bring out that glossy look. Once you have given the paint time to dry (I let it dry overnight), sand the entire surface with 1000 grit sandpaper. Wipe the area down with rubbing alcohol, and repeat with 1500. Rub the piece down and repeat with 2000. At this point, the piece will not be very glossy... it will actually be very dull and hazy looking. This is ok. The next few steps will fix this
 Buffing
Now, there should be no scratches left in the piece. If there are, please go back and fix them. The piece will look slightly dull and hazy, but this is ok. We will now apply some 3M Rubbing Compound to our Terry Cloth. Rub this into the piece until it looks clean and smooth. Clean the entire area with rubbing alcohol. Now, under a nice, bright light we will analyze the piece to make sure that it looks smooth and uniform. If it is not, repeat this step. Then wash with rubbing alcohol.

 Polishing
For this step I used 3M Shine Restorer. It is suggested that you apply some of the shine restorer to a buffing pad on a buffer for this step, but I did not have a buffer, so I simply applied some to a Terry Cloth and buffed the piece by hand. I used small circular motions, eventually going bigger and bigger. Once you finish, the finish should be smooth over the entire surface. It will also be very glossy.
Now, before continuing, we must wax the piece with wax stripper. The buffing compound and shine restorer contain waxes that are used on the finish coat, and these must before remove before we apply the clear coat. Once you wash the surface with this, wash with soap and water, then rubbing alcohol.
 Clear Coat
The clear coat is the final layer that you will apply. It will protect your paint from flakes and dings. It is lighter than the actual paint, and therefore it will run much easier, so you must be especially careful in applying it. Apply it just like the color paint, in several light layers. Be sure to apply it evenly, or it will not look right, and you will have to go back to the buffing stage. I applied 2-3 light coats, then two medium coats. If there is a problem, wait for the clear coat to dry, and sand down to the paint. Then continue from the buffing stage.
 Clear Coat Sanding
Now, the piece will not be smooth and glossy like it was prior to the clear coat. I was afraid of sanding through the clear coat, but after trial and error I found that as long as you don't drop down in grit too much, this shouldn't be an issue. I sanded the surface smooth with 1500 grit, then wet sanded with 1500 and wet sanded with 2000. At this point, the piece will be slightly hazy again. 

  Finishing
Now when the clear coat is done to your satisfaction, you will repeat steps 8 & 9 (buffing and polishing). Clean the piece with rubbing alcohol and allow it to dry. Then apply some 3M Rubbing Compound like in step 8. Clean with rubbing alcohol and apply 3M Finisher Remover like in step 9. Clean the surface with rubbing alcohol (which you are probably sick of by now).
 
I hope this helps