Make sure your hair is around 1 ½” short for an optimal wave, but you can start the brushing process (read on) on short cropped hair if you like. You'll be trimming with short clippers just around your head from this point on for at least six weeks, so make sure to go to a barber you trust.
How short should I cut my waves?
A good rule of thumb is that you should have a close cut, but it shouldn't be short enough to see your scalp. We also recommend getting an edge up since it enhances the wave style when they appear.
What do I tell my barber for waves?
https://www.youtube.com/watch?v=lSqOwmFqtbo
Should I cut my hair with or against the grain?
Starting out, you should cut against the natural grain of the hair as it is the most effective way. If you are only cutting the sides and back with the clipper, just go against the grain, but go over it a few times to make sure it's even. For people with curly hair, you should go both with and against the grain.