There are 11 8mm bolts,what is the rule of thumb for tightening them

Follow the spiral tightening sequence, starting in the middle for non-circular bolt patterns. Tighten each bolt a little bit and then go back and tighten to spec or just snug them up. Don't over-tighten, since the bolts are going into aluminum--allow the gasket to do its job. I think you have a 12-bolt pan.

09 5 1 4 8 12

10 6 2 3 7 11

The exact sequence is not that important on transmission oil pans. I would start in the center, however, and move outward in a criss-cross pattern as much as possible.