Most sleeves will have between 1/2" and 1 1/2" of sleeve cap ease. If your sleeve ease is minor (1/2" or so), you can often get away with easing the sleeve to fit by hand. If you have more ease, you will want to use some stitching to help shrink up the excess fabric before sewing.

Setting in your sleeve

Sleeves can either be set in 'in-the-round' or 'flat'. When sewn in the round, all seams are sewn before the armhole seam. When sewn flat, only shoulder seams are sewn and the sleeve is attached flat. Afterwards, the sleeve and side seam are sewn up.

Saltbox gives instructions for setting in the sleeve flat, which is often an easier way to manage sleeve cap ease. (NOTE: The flat method can sometimes result in a bit of uncomfortable bulk at the underarm. Later in this post, I include instructions for what I call the 'combination method' which gives you the best elements of both flat and in-the-round methods: easy sleeve easing and a smooth underarm seam.)

Even though the sleeve in this tutorial is set in flat, the techniques shown can also be used for sleeves sewn in-the-round.

Method 1: Easing by Hand (small amount of ease)

To start, pin your sleeve to your armhole, right sides together as pictured, with the sleeve curve positioned opposite the armhole curve. Make sure your sleeve notches match on both sides (tip: two notches will always indicate the back sleeve/armhole).