Hi, I'm painting a frame. I have already applied two back-to-back style coats of rustoleum on top of the primer, and I'm thinking I would like another couple of coats of color. What do I do next? Can I just sand the surface of the first two coats and apply more color? Also, as long as I'm on the subject, how long would you recommend I wait before clear coating, and do I have to sand between the color and clear coat. I've been reading a lot of Dr. D's posts and searching the forum, but there is just too much to look through in order to find the answer to my questions.

Sanding is good.

Depends on the paint and how you're drying. Read the directions.

YES!
Use a FINE ScotchBrite pad to scuff the surface, then spray more color.
Take careful notes from the spary can in regards to "flash" time.
In some cases you have to recoat within 2 hours OR wait more than 72 hours, scuf and continue painting.
Clear is the same. If you are not adding decals between the color/clear, then just wait an hour after the last COLOR coat and start with the clear.
Be warned, several coats of rattle-can paint CAN take from 2-6 WEEKS to fully harden.
Test by pressing your thumbnail into the paint at the dropout. If you can leave an impression, it's not done curing yet.

Wait less than 2 hours and just start spraying the clear.
Otherwise, wait the 72 hours, scuf, add decals if desired, then clear.

When spraying the LAST coat of clear, be sure to spray quickly and get all the paint on the frame wet at the same time. This will help the paint flow out to a nice gloss. But you have to be careful. Too much paint too quickly and you'll get runs!

In any event, wait at LEAST 3 months before doing any rubbing or polishing. The harder the paint is, the better the polishing will work.
If you get runs on the final coat, either sand the runs, scuf the whole frame and reshoot some clear OR...
Wait 3 months, sand the runs carefully and polish out the sandscratches.

You can always PM me with specific questions that need quick answers.

Good luck with that and HAVE FUN!

Wow, Dr. Deltron you truly are an amazing resource of painting knowledge. I'll post a pic when I'm done of course, but truly it will not be beautiful as I'm painting it a simple rustoleum brown. Hopefully that will help deter some of the criminal activity Thanks again for the great advice!