What is the best way to paint a pillar?

Are they smooth or fluted, round or square? Smooth I would use a 6" smooth foam roller. Fluted a good badger brush. Tape ceiling and floor around 1st.

You could try painting them with a small roller...that will usually prevent paint lines. Or possibly a sponge brush instead of a bristle brush.

Use a foam roller. and use chalk paint or another textured paint, unless you want a glossy surface.

sounds like someone just did a bad paint job. The first thing, make sure pillars are clean, then sand lightly to remove any ridges that was left by the previous paint job. You didn't say what they're made of, but just prime and paint with paint meant for whatever material your posts are made of. Make sure you stir your paint well, thin coats are better than 1 thick, and a product called flotrol helps with the ridges. Lightly sand in between coats and you should have a flawless paint job.

Also use a GOOD paintbrush. I use Purdy.

Just a suggestion: My Aunt and Uncle used a nice rope to wrap around the posts in their finished basement and it looked so much more polished than had it been painted. They used a nice quality rope and either it came stained a nice color or they stained it themselves, but it looked great!

I would use either the 6" or a 4" foam roller, then drag a brush lightly over the paint to remove any texture or paint lines