I had the same thing happen to my moped. Get some waterproof sand paper, some water, and sand it down a bit. Normal sandpaper does the job just fine, but wetsanding helps deal with all the dust. Just be sure its dry before painting. This gives the paint something to stick to. As for rough spots, if you run your finger over it and you can feel it, when you paint it, you will be able to see it. Hit it with a Rustolium basecoat, white if you want the red to really stand out. Multiple coats are recommended, just make sure 1) layers are pretty dry before adding another, if there’s too much solvent left in the paint, then it will never cure right, and 2) paints are compatible. Some spray paints are made with different bases and when put together, it cracks, peals, bubbles up, looks like hell. Topcoat, and wax it up. If your rattle can skills are decent, it should turn out beautiful. Its not an instant fix, but the rewards are pretty sweet.