craftgrrl | Tshirt Modification - Time for a change, but how do i do it?!

I had a look in the memories section, and i coudln't find anything on this --

I have a few tshirts that i'd like to modify -
they're either too big, or i want to cut the sleeves off without them looking like i inherited them from a trailor park.
I had a tester t on the go, and i quickly realized that cutting too much off gives you gaping holes for arms!

any suggestions on how i can cut the sleeves off of a tshirt, and maybe even turn it into a cap sleeve?

I don't want to start getting scissor happy without getting a few suggestions or how to's !
I do have a sewing machine. I just haven't touched it in awhile!

Thanks so much girls! :)