Once of the main things that will make your painting work look unprofessional is painting the hinges and other hardware. At my apartment project I’m finally to the painting stage. (This is what I do in my “spare” time.. 
Much of my work seems to be at older homes, where it’s a rare thing to find unpainted hardware. Somewhere along the way it was painted to save time.
Don’t do it!
Take the time to remove those window locks, handles, door knobs, strike plates, deadbolts or whatever. The one exception may be the hinges. You can leave them on, but don’t paint them. Put some painters tape on them if that’s easier for you.
Leaving the door on the hinges makes painting the door easier because you can get to both sides and it can dry in place. Just don’t close it until it’s had plenty of time to dry or the paint will stick to the door frame.
After the paint dries, put the hardware on or take the time to upgrade them. Either way it will look much better and more professional to not paint the hardware.
-Peter
