Learning how to draw portraits in Photoshop

I've just been learning Photoshop for the past month or so...and this is the digital art I've made!
I don't know how to draw really, which is why drawing folds is hard for me...Also, I didn't have a Wacom tablet and I had to draw everything with the pen tool...

I'd love to hear your critique and opinions please...thank you.

Wow! Pretty cool stuff you've got! I should say thats a lot of progress if you did all this in photoshop. Anyways have you tried other softwares other than photoshop? Like GIMP..try it out its pretty cool! Also about the folds of the clothes..first you should try to do the folds the traditional way and once you get the hang of it then it will be easy for you to do it digitally. Good job.