First thing you really have to do is to find out what you really have for paint on the bike. You might throw all these polishes, chemicals and elbow grease on it and end up with not much improvement or even a worse paint finish.
Unfortuantely, some manufacturers apply really cheap finishes on their bikes be it thin chrome, thin, flakey, dull paint. and fragile graphics/decals. If you have all these problems on your bike, there isn't much you can do to get a really good looking finsh than just go ahead and repaint the bike with better materials. Just putting more elbow grease into it can just result with you damaging the paint job and graphics, instead of improving it.
So as the saying goes, "try these polishes and cleaning products out first in an insconpicuous area" on the bike (bottom of BB?) before you go whole hog on the frame. Try to start with the mildest procedures first to be safe.... Every bike is different and there's really no universal way of approaching this without some careful experimentation by you first.

Chombi