2) Consider the domino effect.  It's best to write out in advance 
at least a partial timetable of the changes that result from the 
divergence point.

This is, IMHO, the most important thing. I've seen way too many alt. universe
fics where some dramatic changes have been made to some characters, but the 
author still tries to follow the orginal storyline. If you do big changes to
the characters it usually means that things will turn out differently.

I think I'll scream if I see one more fic where a smarter Ranma makes 
exactly the  same mistakes the original did when first meeting Akane for 
exactly the same reasons...
-----------
Jushi, The resident Martian of cyberspace
Jussi.Nikander@alien.nixu.fi
Nabla is your friend.