Key and Clean/sanding body before priming?

Is this really necessary? If so, which sand paper grade should I use? I have Tamiya papers. Thanks!

Without a doubt, always clean the car's body before painting. My process is:

1. Do all the necessary body work that's needed (remove flash, sand, putty in pits or scratches or whatever). If you need to spot prime to check for errors, go ahead, just spray very thinly.

2. Once all your body work's done, wet sand the whole body with a fairly fine grit, maybe a 1200 or so.

3. Fill a bowl with warm water and dish soap, and scrub the entire body with a toothbrush. If the kit is cast in resin, this isn't just to clean off debris and your finger oils--it also removes the release agent from the mold, which paint doesn't like to stick to.

4. Shake it to get rid of most of the water, then pop the body into a large tupperware container with a lid immediately, and let it dry in there for a day or so.

5. Start your priming and painting.

Doing these steps will ensure a really nice even primer and base coat without and little particulates or fisheyes.

Thanks man! Ugh, the mold lines on the Vertex Ridge Soarer are a PITA! maybe I'll post pics of it later. Its going to be a metallic light blue with maybe a metallic black base. The VOLK wheels which I painted bright orange/red with chrome lip.

-Chris