When I was learning how to fold cloth diapers, the trifold technique is the first fold I learned, and it's still the one that works best from my son and me.
It provides an extra bit of coverage in the front and it's a secure fold, so you could easily fold several diapers ahead of time and have them ready to go at diaper changing time.
Diaper fasteners like Snappis or diaper pins can't easily be used with this fold, so you'll need to use a wrap style diaper cover secured snugly to your baby to keep the prefold in place if you use the trifold technique.
1. Lay the diaper out flat.
2. Fold about 1/4 of the bottom edge of the diaper upwards. You can adjust this fold to fit your baby. With practice, you'll know exactly how much to fold up to suit your baby's build.
3. Fold one long edge of the prefold along the seam sewn up the prefold (so the edge lays on the middle section of the prefold).
4. Fold the other long edge the same way, along the seam sewn up the prefold, and tuck the bottom of the edge into the pocket formed by the first two folds (see photo below for clarification).
OPTIONAL: If you'd like to have a few diapers folded ahead of time, you can fold several diapers up to this step so you won't have to do any folding at diaper changing time. The fold is very secure, so the prefolds won't become unfolded easily.
5. Lay the prefold on your diaper cover and tuck the front end of the prefold into the front pocket of the diaper cover.
6. Add a diaper liner or diaper doubler if you use them.
7. Lay your baby on top of the diaper and snugly, but comfortably secure the diaper cover on your baby ensuring none of the prefold is sticking out of the diaper cover (you especially don't want any prefold sticking out at the front if you're diapering a boy, or at the back if you're diapering a girl). Ensure there's a good fit around the legs.
Lay the prefold out flat.
Fold up the bottom of the prefold to size for your baby.
Fold over one third of the prefold
Tuck the bottom edge of the diaper into the fold to secure as you fold over the other third of the diaper.
Folded and diaper with bottom fold tucked in. You can fold several diapers ahead to this point if you like.
Place the prefold in the diaper cover.
For general tips on folding diapers, see Folding Cloth Diapers