measure around your shoulder (and under your armpit). for this example, our measurement will be 15 inches.

you'll also want to measure your upper arm. for this example, our upper arm measures 11 inches.

and don't forget to measure your bust and waist.

a basic sleeve is shaped like this. you'll need two of these, and i recommend using a fabric with some stretch.

If you don't know how to make a sleeve, I strongly suggest you either BUY a pattern with sleeves, or cut apart an old shirt to make a sleeve pattern yourself, because they are tricky, goofy-shaped little dudes, and I can not instruct you on how to make one other than the advice above.

add an inch or so to each measurement, unless you have very stretchy fabric and want very tight sleeves.

the top bell curve corresponds with the measurement of your shoulder-armpit.

the widest part should correspond with your upper arm measurement.

fold it in half and sew the sides together.

grab you big old t-shirt and mark it like so. the shape is like a sleeveless tee. make sure the bust and waist correspond with your measurements.

cut the front and back piece out.

the back piece should be cut almost straight across. don't cut a big dip in the neck like the front piece.

you can cut the front piece down the center if you want to add a zipper.

Sew the front and back pieces together, and then attach your sleeves.

If you've never attached sleeves before, read through this tut first: Easy Sleeves!

make a pattern roughly shaped like this, and cut two. if you are putting a zipper down the front of your hoodie, you want the bottom of the hood to be the same measurement as the neckhole.

if you're not putting in a zipper, you can make the hood slightly larger, so it crosses over itself.