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Stitch toward yourself.
Lubricate the awl before every stitch. Some use beeswax, others paraffin, others soap.
Hold the welt flat while stitching, rather than stretching it, so you don’t have to flatten it later. (Lisa Sorrell video on just this problem)
When lasting over the lap, it can help to hold the shoe across the lap when welting the toe.
Tighten each stiff vigorously. Wrap the thread around the awl on one side and the hand on the other.