Hmm i can give you realy basic advice ^^ when you have a planet with a lot of people in (like the capital, or independant population) try to keep a very tax in. Like that the polpulation will grow as far faster, it's realy valuable for the long term! 

My favourite is the Securan race , with 23% base grow rate and the Utopian governement, they are definitely the sexiest race in the galaxy [8D] and it makes the expension realy easy.

Well im actually a noob and i play in peaceful galaxies, with Shandars as ally ^^