Do I have to sand a wood dresser?

If you sand it, not only will the surface be smoother - no splinters -, but any primer or paint will adhere to it better and the final surface will be nicer. You don't need to go crazy with it, just clean the surface really well, let it dry and then lightly sand it. Since you're refinishing rather than working on an unfinished piece, sand it just enough to take the shine off the surface. You probably don't even need a primer, unless you have some serious stains.

I personally would also use a belt sander with a coarse paper and then when the paint is gone go to sanding by hand and change down to a fine paper to give a smooth finish, personally i love natural wood so I would use a light or neutral wax. hope i could be of help XD ....also no need for sealant if you do paint but you could use a gloss paint to make cleaning easier

It depends on the finish. Is it painted already or is it stained or is it unfinished wood?

Painted: light sanding with fine grit paper, wipe with a tack cloth. Paint.

Stained: prime with oil based primer--maybe two coats for good coverage --paint.

Unfinished: sand like a dog, tack, fine sand, prime, paint

If you want a smooth finish sand it down.. to just paint it prime it and then paint it

Wipe it down with liquid sandpaper, then repaint.

i would only sand it to get rid of any scratches

problematic step. search using google. that will help!