How to paint a cement patio?

if you can, get all the old paint off, then you want a paint made just for cement, and a paint roller. if you don't want to paint it, there are clear sealants that also roll on and seal the concrete. big box diy have it.

There is a sealer/paint that is used for garage floors and concrete, you just roll it on, I'm not sure the name of it though. Just make sure the surface is clean and dry before applying anything to it.

Depending on how large the patio is, you may also be ale to get away with buying a bag of cement mix and fixing any holes/cracks that way! It may be the cheaper solution

Spud, a pressure washer might get the paint off for you. If you don't have one, or someone to borrow from, you could rent one. Just depends how big your patio is and how much money you want to invest. Good luck.