It's easy really, there are many hairstyles.

of course you draw the head first

then bangs! They can be spiky,straight, wavy or curly!

then you do the top part of the hair!
Again in can be spiky,straight, wavy or curly!

then you do the bottom part! As you can see I drew spiky hair :>

Here's if you wanna do straight to spiky hair..

You draw straight bangs first.

then you do the other side and draw the hair spiky at the bottom.

And you the the other side behind the bangs.
I also use jaltoids and nettyscrible (from YouTube) to draw hair ^^

^^^Nettyscrible^^^

^^Jaltoid^^