When we bought our house, our kitchen cupboards were an ugly, scratched, dark brown. I had already been dreaming of a dark blue kitchen with white cupboards, so I had no qualms about painting them. I did a little bit of reading online, then dove right in. We had four basic steps, after removing the doors:
1 - Wash
2 - Sand
3 - Prime
4 - Paint
Wash: Really take your time with this step. We just kind of lightly wiped them down, and this worked okay for some areas and not so well for others. If there's some grease buildup (which there will be in a kitchen), make sure you clean all of that off so that the paint sticks well; we didn't clean the doors above the stove as well as we should have, and the paint cracked, so really get those puppies clean! See if you can find a detergent with TSP in it to cut through the grime.
Sand: Don't worry about sanding everything down to bare wood, just sand enough to rough up the surface so that the paint will stick better. We used both sandpaper and steel wool for this step. If there are any areas that were hard to clean, sand these really well.
Prime: I don't remember what brand of primer we used, but make sure that it is good at covering dark finishes.
Paint: This is the most time-consuming part of the whole process. We used a glossy finish white paint, but I think semigloss or satin finish would work just as well. After some experimentation, we discovered that foam rollers and brushes were the best for this job; they leave a relatively smooth finish and are easy to work with. We just bought ours at the dollar store. I think we did two coats of paint on our cupboards. We didn't paint the insides of the cupboards themselves, but we did paint both sides of the cupboard doors.
Optional -- Add a clear protective coat: We didn't do this, but our paint job has held up just fine over the last five years. It will add a little bit of protection, though, especially if you have sticky little fingers touching the cupboards.
So, was it a big project? Yes. Am I happy with the way it turned out? Yes. Would I do it again? Probably. Now that we've done it once and have learned from our mistakes, I think I'd be willing to try it again. Take your time and you'll do just fine. Have fun sprucing up your cupboards!
We don't really have any photos of the kitchen as we were painting the cupboards, so I'll just re-post the "after" picture. :)