I want to paint my bathroom cabinets, what do I need to do?

Really depends what kind of paint you will be using. You can deal with wax

Hey there! I think that sealing them is only necessary if you aren't using a semi gloss or gloss paint, as they are the most durable for bathrooms and kitchens. The trend now is chalk based paint for more of a shabby chic look so it might be a good option also because it is slightly shabby and will look good as it shabbies up more. You could always go for a highly protective layer of varnish or polyurethane though. They make some that are excellent for wet areas like bathrooms. At our house we just use semi gloss and it holds up very well!

I would suggest sanding the cabinets slightly and then using a primer to seal the cabinets before painting. You can find primers at the paint store.

What are the cabinets made out of wood, laminate?

Lightly sand,clean,prime with two coats of Kilz or Zinser with a foam brush allowing to dry in-between.Paint ,dru and seal with a non-yellowing polycrylic.

If using chalk paint most of them you don't have to sand first. Make sure to clean the cabinets very well and if using other type of paints such as semi gloss or flat paint, most have a primer in them already and you can skip the priming all together.

Remove the doors and hardware. Mark the doors and cabinets with tape where they go. Lightly sand the doors and cabinets to remove any gloss and roughen the surface for paint. Prime with a stain blocking primer like Zinsser 123. Then paint with your color. Seal with at least three coats with a water based polyurethane. Use a small foam roller and foam brush for a smooth finish.