Before you cut out the bodice pattern pieces:
You might want to lengthen the front and back bodice pieces. The blouse I’m wearing in the pictures is made from pattern pieces not lengthened, and it is slightly short on me, especially wearing it with high waisted jeans. It ends just at my natural waist. So I suggest that if you intend to wear your blouse with jeans or any bottom that ends below your natural waist, lengthen it 2-3 inches. If you plan to wear the blouse with a skirt that sits at the waist and has a waistband rising even higher, you might be fine with the bodice not lengthened, though.
To sew up the bodice and sleeves, just follow the instructions, the steps are the same. The first thing different is how to attach the waistband.
1) Join the two waistband pieces (on a short side).