My brother gave this shirt to me for Christmas and I really like the message so I decided to cut it up. I should explain: this is the shirt I started with. 
It’s baggy and wide and didn’t fit all that great. So I resized and gave it a more feminine shape. Here’s how I did it:
I started by trimming off the ribbing around the neck line because I like my neck lines a bit wider and a smidge lower. Be careful, because t-shirts stretch very easily once you cut off the ribbing. I only cut off about ¼ of an inch in addition to the edging and it was perfect.
Next, find a shirt the fits you well. I used this blue camo shirt. It worked well, but it was a bit too stretchy. Use a shirt that fits without being stretched too much. If your pattern shirt stretches more than the shirt you are repurposing, you will end up making your new shirt too tight.
Flip the shirt you are upcycling inside out and lay it out flat. Lay your pattern shirt over the upcyle shirt and line up the bottom of the arm holes. You can use the pattern shirt as a template to trim the sleeves a bit shorter if you want to. Trace along the edge of the pattern shirt, making it about ½ an inch wider for seam allowance.
Pin the shirt along the line so you can sew it. This is important: DO NOT cut the shirt yet- the edges will roll up and make sewing more difficult and you won’t be able to redo your seam if you make a mistake.
Once your shirt is pinned, sew from the arm holes down to the hem on both sides. Try it on, and if it fits, congratulations! Trim the extra fabric away and surge both edges (not needed, but it’s a nice finish.)
