I personally wouldn't rattle can anything other than a frame, and that's if it is a beater. The components on a bicycle move too much and will eventually just scratch or peel anyway, looking much worse in the end. Buttttt if you are going to rattle can something, I've found it takes the least amount of work to make flat or matte paints look decent. Painting is mostly prep work, start by sanding the components, not only to get them smooth, but to rough up the surface so the primer will stick. This is key, as well as keeping a clean surface and area, so wipe down everything before shooting any paint. After you've got your primer down (wet sanding between coats) and have let it dry completely get your color. There are a wide range of aero-paint qualities too, so that is also something to consider. When applying be sure to use long smooth strokes, going just past the end of whatever component you are painting. Stopping early will leave you with an uneven coat and make it that much harder when you're wet sanding. Again wet sand between coats, the more coats of paint you get down and the smoother you get it the better the results will be. I usually am between 5-7 coats before it's said and done. The clear coat you use also plays an important role in the finish you end up with. Choose the appropriate gloss, matte, or flat clear. I would recommend something that is a ''hard clear coat''. After the paint has cured you can cut and buff if you feel the need. Take your time if you're serious about the outcome... I've gotten some pretty decent results with a quality aerosol paint can.

If you don't really care, screw everything I just said and leave everything on and just paint the whole bike in a zig-zag pattern (don't do this), Have fun!