For a solid T/D, I go from the top middle towards the back, then from the top middle towards the front. Then go from top to bottom.

If the T/D has stringers, I tack 3-4 places along the top, then 3-4 places at bottom. When satisfied with results (as few wrinkles as possible), I seal all edges, then use gun to shrink material. A word of caution; if the stringers are not real stout, the shrinking process can deform them. Watch them closely!