Critique my drawing skills, Southperry

The most important thing with art is to keep trying!

Okay, from now on I will keep structure in mind (and start out with drawing the 3 seperate parts of the face?).

Try not to think of things as "separate". It's hard for me to explain when we're just looking at a face, but that rule of thirds is just to help you see the different ratios of a face. Trying looking at other people's faces as well, like Jay Leno. It's also a tool used to when you're trying to caricature someone!

It's important to look at the image as a whole and then break it down because everything is related to each other. If you ever do life drawing, knowing landmarks will help understand how things relate to each other better.

If you do an image piece by piece, say, you spend an hour doing the eye and that's all you have done, your other areas will suffer. Instead, as others have mentioned, lightly go over where you want things to be placed and keep adjusting in this stage. That's not to say you can't adjust things later on, but it's important you create a good base to work on. Try to work on the entire image at once. That sounds daunting, but it just means don't focus on one key part at a time or your proportions will look completely off.

I think the forehead is larger because I put the eyes too high?

Yeah, I think her forehead is a little over 1/3 of her face, her brow to bottom of nose is about 1/3, and her bottom of nose to chin is a little under 1/3.