Here are some hints and suggestions about powder coating, specifically a frame, but it applies to most items.
Briefly, the part to be coated is masked, sandblasted, and hung on a rack that is electrically charged. It is sprayed by hand, covers the part as a dry paint coating that is electrically drawn to the electric charge. Then it is baked at around 300-350 degrees F. Usually, the hotter its baked, the better it flows, and the smoother it is.
Prep it at home. If you are doing a frame, clean the grease out around the swinging arm and neck - you don't want it melting and leaking out when it's baking. Don't leave anything plastic or rubber on it.
Seal the steering neck with a long bolt and large washers, and swingarm pivot holes with bolts, washers, and nuts. Some sandblast debris will still get in.
Fill any threaded hole with old spare bolts so sand and paint don't get inside. Otherwise, you'll have to clean them out with a thread tap afterwards. Put nuts over exposed threads, like shock mounts.
If there are exposed surfaces you can't protect, have the powder coater mask them with his tape that wont melt from the heat or leave a residue - like threads and bearing surfaces on stems. Or the inside of triple clamps where the forks slide through.
Use a bolt/washer/nut to block off the area where the engine and harness grounds are.
Find a powder coater who sandblasts on the premises, and will paint it soon afterwards. A bare frame starts corroding quickly, and once it does, the corrosion will keep growing under the finished powder coat. I've seen it crack the paint from underneath months later. Don't try to save money by sandblasting it yourself at home.
When you drop it off at the powder coaters, lay the pieces on the ground, take pictures of the bunch, and count them. Make sure they list how many pieces you have.
When you take it home, and take the bolts out, blow the holes out with compressed air. You may still need to run a tap through them. Because there are holes between the frame and steering tube, sandblast dust may get into the bearings - block the holes with some foam or rubber plugs.
