I have old, old, kitchen cabinets, they are laminate with the fake dark wood look. Can these be painted?

Can anyone please advise me on the steps to painting the inside of my garage walls so I do a good job and the paint adheres well? My garage is 22 years old, is finished in wallboard and was painted a very very long time ago. Alot of paint is flaking, some areas are large. I think it was only painted with flat paint. Do I *Clean walls of dirt, spider webs, etc.(should TSP be used?) *Prep walls by sanding loose paint, filling holes, etc. (some areas are very large where the paint is flaking and when I sand them they continue to flake more and more) *Prime walls? What kind of primer for garage? *Then paint the walls? What kind of paint? The marks etc. on the walls seem like they will be hard to cover up, is there certain primer and/or paint that works best for garages? Thanks in advance for help.