My friend Carol and I recently gave a face-lift to a porch. As you can see, paint was flaking and peeling from at least six layers of colors. I actually thought it rather pretty/interesting after sanding and scraping (below), but the homeowner wanted a fresh, clean look for an upcoming party. We gave it a cheery flagstone motif and then sealed it with two coats of an exterior urethane that has ultraviolet resistance.
A floor job like this requires a lot of preparation: scraping, sanding, scraping again - and then using a chemical deglosser to aid in paint adhesion. Special floor paint is used and then the entire floor sealed and allowed to cure. Ideally, no furniture should be place on the floor for at least two weeks, though foot traffic is okay after a couple of days.