I get conflicting messages about how tight the luff tension should be. In the end I go with what the sailmaker says (figure of all the opinions, that should be the one you pay attention too). The sheeting angle should point to a point on the luff about 1/3 up from the tack (once again, sailmaker told me this and may or may not be unique to my spin cut). Some people don't like telltales on their spins, but I do. Trim the spin so it is on the verge of collapsing and/or the leeward tale is flying. The only way to get speed out of a spin is to be really agressive at trimming or driving. If you have the opportunity to have someone crew for you who really pays attention to the constant trimming of the spin (or concentrate on it yourself) then you will fly. Compare that speed and feeling to when sailing with less attention to the trimming.
I get much more confused these days about how the main is supposed to look downwind. <img src="http://www.catsailor.com/forums/images/graemlins/confused.gif" alt="" />