What I did not learn how to do properly was a narrow shoulder pattern adjustment. Up until now, I simply shave off a bit of the pattern on the armscye near the shoulder and taper it to the cutting line near the middle of the armscye. It's always hard to tell if I've taken off too much or how it will affect the fit of the sleeve when I sew it into the armscye. Sometimes I end up with too many gathers in the sleeve.
This video tutorial from the sewing space explains the shoulder adjustment perfectly.
Lena explains that if you alter the shoulder line by more than 2 cm then the sleeve pattern will need to be adjusted also.