If you are looking to paint your floor there are a few MUST steps. Its all about the surface preparation. You first need to degrease and steam clean the concrete. Next you should really have it shot blasted or sand blasted to create an anchor pattern to promote good adhesion. My firm does industrial epoxy floors for the likes of Fait Chrysler and for other industrial service conditions.
You can buy a good 100% solids 2 part epoxy from PPG (Dulux Stores) or Sherwin Williams. Ask for an industrial sales rep. Lighter duty water based epoxies are ok too but will definitely not perform as well as the solvent based coatings. Treat the cracks first with epoxy filler then sand with floor maintainer. Apply a 3 to 5 mil prime coat of the epoxy by roller. Back roll five minutes after application. Sand out and off gassing bubbles. Apply a second coat. Add # 30-60 sand broadcast to make the floor non skid. Sweep off excess sand after the paint has cured. Apply a topcoat 3 to 5 mils.
We don't perform work Business to direct public but here is a good link to how to restore concrete and application of epoxy floor coatings:
Great description of "how to do it the right way". Lots of work but if it is done right it will (hopefully) last.