Generally, strategy should vary with map size and numbers of planets - for example,
- in smaller maps, the grab for planets doesn't take long, and you can afford to BUY your colonists from Mitrosoft, and need every turn that this saves you (buy another colonist from Earth every turn until your startign cash is gone...)
- while on larger maps, colonization takes longer, and the short term speed of the above strategy isn't worth the long term cost of paying Mitrosoft PLUS you just need more colonists than that strategy can provide (here, crank military spending to 60-80-or even-100, depending on how aggressively you want to colonise, and churn out a colonist every third turn or so...)
There are lots of threads, and lots of ideas, on the Strategies forum (look for headings like yours!) - just beware that some players always play the same settings [large, common, etc], so while thier views may be right for them, they may not apply to you (and they may not understand that).
~SDC~