Which kind of sandpaper do I use in preparation for painting cabinets?

Medium and fine grades of sandpaper are generally used in refinishing furniture and antiques. Coarse grits (those under #100) damage a fine wood finish. Medium grits, such as #120 and #150, are useful for removing old finish or scratches.

I agree with Em, start with a medium grind and then finish with a fine, it will scuff up the surface but still give you a smooth result for paint.

When I have scruffed up cabinets and furniture before priming I have used just a fine sandpaper and a fine and extra fine sandpaper block. It's enough of a grit to scruff up the cabinets and dull down any clear finish without damaging the wood. Clean them well with a vacuum and then wash them with a damp rag and some dish soap, let them dry, and prime them with a primer like Kilz before you paint.

"T" --- I'm another one that agrees with Em!!

You've gotten some good advice here. I'd just like to add that I really like using sandpaper blocks, as someone else mentioned. They're so much easier to hold and use than regular sand paper, and you can get them in a variety of grits.

If you only want to scuff for paint to adhere, I use fine steel wool then clean with denatured alcohol. I've never had any issues and it's much less of a mess than sandpaper.

Thanks guys for your amazing answers.

I always prefer 120 grits. But what kinds of paint are you using. With chalk paint or chalky finish paint, you don't even need sand paper at all. Here is a complete tutorial on chalk paint. https://bushraslifestyle.com/how-to-paint-a-dresser/