I use different parts in a lot of my hairstyles so I thought I'd kill some time while we were in our hotel and get pictures of my favorites.
This is the "Butt Crack" (Thanks to my sis-in-law for the great name.) :)
This is the "Zig Zag". (My princess thinks they look like "greater" and "less than" signs.)
You can make your angle at whatever degree you like and they can be as tight or as wide as you like.
Here's the "Swirlie".
Just make the "S" shape down the scalp.
We call this one "Blocks" because it's kind of like blocks stacked on top of each other.
Just create 90 degree angles down the head - making sure to keep the lines parallel.
This last one is the "Heartbeat".
Notice how it's only on the top half of the head and the bottom is the "Butt Crack" part. You can mix all different parts together for a different look.
This is the best comb to use for making parts. It's a rat-tailed comb that I picked up at Sally's Beauty Supply for a couple bucks but I'm sure you can find it other places as well. I use this comb for everything and would suggest picking one up if you don't already have one.
Remember that parts can be made anywhere on the head and do not need to always be centered. They also don't need to cover the whole head. Be creative and you can come up with all sorts of fun stuff.