question on expansion

[John]

I like the idea of the expansion capability coming with OOTP2007. But what's the best way to proceed with expansion (fantasy player, not historical).

I'm starting with 20 teams (2 sub leagues, 2 divisions each) and will expand by 2 at some point, then again by 2 at a later point). Should I:
* set up my universe with some independant teams at each level, and then use them as expansion teams later on?
* expand the amatuer draft by a few rounds in the few seasons before expansion to produce some extra players?
* any thoughts on how to fill the minors (AAA, AA, A and Rookie) for each expansion team with decent players?

Any thoughts on how anyone has done an expansion in the past would be more than appreciated.