Basically, what everyone has been saying is correct. The sandpaper available through auto stores is the best route to go, though it is also available at hardware stores.
Some tips - the higher the grit #, the finer the grit. Generally, you want to work your way up. The coarser stuff will remove the drips, but will also scratch the surface around the drips. Starting off with 2000 grit will take a LOT of elbow grease to see any results. If the drips are severe, I would start out with 400 grit and try to contain the sanding to just the area around the drips. Once they are reduced, switch to 600 grit and widen the area you are sanding (this will help remove and stray scratches and feather in your work). Once that is done, move up to 1500 grit. You should be using lot of water and using lighter pressure as you go. Believe it or not, by listen carefully, you'll hear a slight change in pitch as you sand. That will be a clue that you've sanded a given area evenly. Give it a good washing and see if you are satisfied. I have gotten excellent results by spraying on a thick coat of paint and then sanding/buffing it out.
If you need to respray it, try this. Shake up the can o' krylon a bit, and then let it stand in a shallow tray of warm (not HOT) water for a couple of minutes. This will help soften the paint and also serve to pressurize the can a bit more, resulting in a finer spray. Also, you may have spraying a bit to close, so move back a bit.
Post a photo of the trouble area and we'll chime in with more tips.
Gene
