Well, we know that every race has a different AI that plays the game a different way. I figured it would be nice if we ironed out just HOW it is that each race plays, so that you will know what you are up against when you see them.
Here is what I know for sure so far.
1. The Terrans hang back and play well with others. You dont usually see the Terrans taking an aggressive stance in the game.. they will colonize their planets, protect their area, and focus on diplomacy and technology. If you ignore them, you may regret it later when they decide to make their move.
my personal recommendation: I have had good luck beating them with influence. Since they take a passive stance towards the civs around them, I was able to aggresively build influence starbases on my border with them, and disrupt their "fortress of solitude". Ive also found that its fun to bribe another civ to go to war with them

..just to keep them on their toes..and stop them from building up too much.
2. The Altarians are hippies. Their thing seems to be tree hugging, and getting others to hug trees with them. influence is their game. I cant stand being next to the Altarians.. they are the nosey neighbors of the universe. Always poking their influence starbases in my territory..and parking their ships right inside my border.
My personal recommendation: Soon as you see that they are sharing a border with you.. build 2-3 influence bases on that border and start pumping them up. Later on, I will usually find some excuse to go "convince" them to stop brainwashing my citizens.. usually with a stern beating.
3. The Torians aint nothing but mammals so they do it like they do on the discovery channel. Seriously..they are like bunnies. Every time I get a Torian planet it is filled with an unhealthy amount of farms... how they function with so many citizens is beyond me. Id never be able to keep my approval rating up.
My Personal Recommendation: I dont really have one. Torians are so dang cute and friendly that I usually either ally with them, or watch them get slaughtered. They dont seem to do very well on large maps with lots of opponents..maybe they are better on small scale maps.. i dunno. Every time ive played against them on a 9 race map though...they have stayed in the "Weak, Weak" range for the entire game, or been eliminated early.
NOTE: Im still new to the game too.. so dont go writing any of this in stone..this is just how I have perceived things.
so..post your own thoughts on races and how they are most likely to act when you are playing against them.