I have an inexpensive knock down dresser that I'd like to paint, but it has a very glossy finish. I'm not sure how to prepare the surface for painting. I can see from some of the slightly damaged areas that it's really nothing more than pressed cardboard. I'm also not sure of the best way to repair the damaged areas, would spackle work?

It would probably depend on what the damage is to the dresser if spackle would work. Are they just small holes? If so, spackle would work...get the non-shrinking kind. Otherwise, I would sand some first......you don't have to go overboard but just to rough up the surface. Then go buy a good quality primer like Zinser 123. I find it helps to sand very lightly with very fine sanspaper after I have primed. Then you will be ready to paint.