Tissue fitting is crucial for many reasons but most especially for getting the correct shoulder length. The shoulder area and sleeve is a common problem area for many.
Pin your front and back pattern pieces at the shoulder and then pin or tape the center fronts/backs to your cf/cb.
Now re-fit your shoulder for slope.
Then find your shoulder point (this is that place where your shoulder and arm meet) and mark the place that is 5/8 of an inch past that point which is for your seam.
I then continue marking all the way down my armhole which hopefully is close to one of the lines that is already printed.
Make any other adjustments at neckline/centerfront/side seam.
Go to your table and smoothly connect all your lines (maybe you need a different color marker at this point).
You must now make corresponding corrections to your sleeve/facings and anything else that is sewn to the new seam lines.
This requires practice and you will have to try it several times to get it just right but it is worth the investment. I love having clothing that has well placed sleeves and correct shoulder lengths.
Often , I notice how too-long-shoulders causes the "unmade-bed" look.