yeah, that's the easiest way if you want to play military in the civilization stage... if you want economic make friends with everyone and if you want religious do half and half... same things goes for tribal stage, kill everyone = military, ally everyone =economic and half and half = religious.
yes, I have played through Spore a few too many times.
And yet you goofed. It's military = attack everything, religious = befriend evrything, economic = half and half.
A few solid pieces of advice I can offer:
1) Evolve constantly. The creatures move up pretty quick in difficulty, especially the social ones.
2) Charm the Alphas. These always will give you a functional part, so always go for these first.
3) Stack the odds in your favor. Ally with as many creatures that are beneficial to your approach as possible and isolate your target. The number of creatures involved is relevant to the likelihood of success. For example, trying to charm 3+ social creatures by yourself just doesn't happen. While charming a lone one with 2-3 social allies can become instantaneous.