Take your shirt and position it along your waist line. If you have curvy hips, I recommend you use a shirt that's a little bigger than what you usually wear. (Sorry for the bad pic!)
Start buttoning up! It's best to start from the bottom. Keep buttoning until it feels too tight.
Take the sleeves and tie them into a knot or if they seem too short to do so, tuck them in. And you're done!