Oh, you want to learn how to make vexel images?
I shall gladly teach.
What I can tell you, you're best bet would be with using the Pen tool. The Illustrator version is GOD AWFUL compared to Photoshop.
I worked primarily with the PS Pen tool, so that's just my style and preference, I guess.
BUT, with any image, I start with the outlines.
Nowadays, I begin with making one LARGE outline so that if I were to fill the path, it'd be one solid color blob. I make a second path on the inside which will have all the details. It can be a bit time consuming, because of a lack of a better method I found, but if you want strong outlines with a decent variance of weight, that's how I do it.
However you make your outlines is your own doing, you could just draw simple lines and apply a Stroke for an outline.
Making color layers has its own method, but if you keep each specific color to its own layer, it's much easier to manage.
Then, you can add a single 35-50% opacity black layer for a simple cel-shaded look.
That's all I can mention in a single post, but I'd like to make a video example, just to show you more. :]