I am extending the length of my back porch and therefore the roof over
it and am thinking about the roofing(asphalt shingles).

I figure I can tuck the last new row of shingles up under a row of the
existing house shingles. But I'm wondering about a good way to weave
the new rows of shingles on the new part of the porch together with the
rows of shingles on the old part of the porch.

Does anyone know a good technique or a good reference book that might
cover it?

Thanks.

RonT