OK, Let's clear something since the start: : The real purpose of this tutorial is to help you to avoid silly and typical mistakes, not to teach you how to be "cool" or how to be "Better than that guy" (no, not THAT guy, the OTHER guy) right off the bat.

This tutorial will include funny (and harsh) graphical examples of What Not To Do, and Why You Shouldn't Do It, oriented to avoid future problems and failures to the novice Authors, but that's all, the rest (and the best) is up to you, and to your own effort and dedication.
Sorry, dude. But real practice is the one and only way to improve.  So... are you ready? Yes?
Cool! Let's start with the lessons, then!

Lesson One! Lesson Two! Lesson Three! Lesson Four! Lesson Five!
Lesson Six! Lesson Seven! Lesson Eight! Lesson Nine! Lesson Ten!
Lesson 11! Lesson 12! Lesson 13!

If you want to learn the basics, then you should check Bob and George's basic tutorials, and if you want to learn how to rip sprites and backgrounds, then check The Spriters Resource's tutorials. Good material and good sites, worth to be visited and frequented, eh?
Yes, that's why I didn't include the same material  here.