The #1 piece of advice I can give you is to get the paint I used. The paint store lady swore by this, and boy was she right! I guess she works there for a reason. I did nothing to this door but wipe it down with some light soap and water. No prep, no sanding, no priming. As a matter of fact, there is no priming needed for this paint. I only bought a quart of it, and it has lasted through the back door, my barstools, and most of my bathroom cabinets. I still have about 1/4 left!
DIY: We have outdated hardware all throughout our home since our house was built in the mid 90's. We are on a budget, so a handy friend of mine told me to spray paint everything. The guy at Home Depot recommended this spray paint, and to use steel wool on the metal to help with saturation. It'll be interesting to see how it holds up with wear and tear, but for now I'm impressed!