I prefer to hand baste the seams together before stitching. Although it takes extra time, hand-basting will allow you to test the fit of the garment and make any necessary alterations. Hand-basting also provides the control needed to make sure that garment pieces are perfectly matched and don't move when you are ready to machine stitch. Baste just a fraction to the inside of the stitching line. This makes it easier to remove the basting threads after you sew the seam.
For machine stitching use a stitch length of 2‑2.5mm. To help deal with some of the bulk, grade the seam allowances and understitch. On my jacket I under stitched the lapels to keep the edges flat. If your fabric ravels easily use caution when trimming, clipping and grading. Do not trim or clip too closely to the stitching line.