Zippers are my least favorite thing to do when sewing. Sleeves are my second least favorite. Luckily, just like zippers, there is an easier way than how most people are doing them.
The sketch on the top left shows how most patterns ask you to insert your sleeves. Create your bodice, sew the side seam up, create your sleeve, sew it shut and then try and cleanly put the two together. I’m pretty sure that the patterns makers chuckle a little thinking about how many frustrated sewers they’re creating when they put that in there.
The bottom two sketches show the easier way. Start by sewing your bodice pieces together at the shoulder seam. Leave the side seam open. Lay the two pieces flat and pin your (unsewn) sleeve piece to the armhole. Sew together and then sew from hem to sleeve cuff (or the other way around) treating the whole thing as one seam.
I do want to put a tiny caveat in here, that doing this does change the fit of the garment very, very slightly. Basically, the way most pattern makers have you put the sleeves in gives you a hair more give in the armpit. If you find that becomes an issue for you, certainly, switch back to the two finished pieces method, but if not, this way makes fitting in ease and generally fitting together two funky shaped pieces far easier.
As always, please let me know if you have any questions about this. And guys, please, please let me know what you struggle with in your sewing. I’m starting to run out of ideas for tutorials!