I used to be a painter. If you do it right, you will spend far more time in preparation than you actually spend painting. This is the “secret” of professional work: an ounce of prevention is worth a pound of cure.
Here are some random tips.
Get everything out of the room you are going to paint. Can’t or don’t want to do that? You’re already in trouble. There are a half-dozen great reasons for doing this, which I will be happy to explain if necessary.
Cover everything. Absolutely everything. Every square foot of floor, no matter how far away from the wall, every square inch of window. Cover the footpath going into and through the next room.
Have a pair of shoes you use in the room you’re painting, which you take off before you leave the room. I kid you not: bad professionals spend as much time cleaning up after themselves–or concealing the damage they’ve done–as they do actually painting. I should know: I worked with 'em, and cleaned up after 'em.
If you’re going to spackle, don’t use Spackle! Don’t use any vinyl-based filling materials. Instead, get some of that 20-minute E-Z Sand, which comes powdered in a bag, and use that. You can sand it flat and do a really nice job with a minimum of experience, if you take the time to follow the directions printed on the bag. The vinyl stuff will make your room look like a Clifford Styll painting.
Tape up the windows exceptionally well. One trick is to use a lot of masking tape, then use a razor blade to cut away the tape which is stuck to the stuff you want to paint. If you are going to the super-flash job, remove the brass window hardware as well. Number each window and put the hardware in separate numbered Ziploc bags. Also, as you finish, remember to razor blade all the moving parts of the window before you open it. Otherwise, the job’s ruined.
The basic method that worked the best for me was this: move, cover, tape, tape, tape, tape, caulk, spackle, sand, dust, quit. Come back later, cover all the spots you missed the day before, then cut, cut again, and roll. Some will disagree with me on the order but few will disagree with the preparation. A huge number of jobs go unfinished because once that crap is on the walls, the job seems to be done. Preparation goes a long way toward actually achieving that.
Since you’ve spent an entire day preparing, clean up can take less than a half an hour, but you should really wait a day before you clean up. It’s your own place, so do it one room at a time, and expect it to take time.