Hi there,
A couple of newbie tips:-
1) Play on a low level of difficulty to get into the game, the AI is very good, normal difficulty is like very hard on most other games.
2) Computer players don't cheat, anything they do, u can do as well apparently they just maximise there resources at 100% or near it even on lower levels of difficulty.
3) Put spending upto 100%, try to keep your planets morale at 100% for population growth for as long as possible early in the game. Don't be worried about being -150 bc's in the red every turn so long as u have a sizeable bank balance. It should balance out later. I have never in any game i have played EVER lowered my spending below 100%, so its possible to keep it there the entire game.
4) Grab as many planets as possible early in the game. Consider designing yr own colony ships, speed is a very, very important factor on any ship. It gives u a tactical advantage over computer players.
5) As soon as u colonise a planet, buy a starport, don't miss out on any ship production.
6) Defend your colonies with at least 1att basic fighter.
7) Use diplomacy to look at the techs alien races have got, then research something they have not got. If your in contact with 5 races u could trade this 1 tech for 5 other techs+. Instant catch up! If u have a large treasury consider buying techs via diplomacy screen.
8) I find having the sliders for military, social and research at 10-10-80 etc depending which areas u r concentrating on at the time is a very good idea. U continue to develop in every area. Play about with them, often if u r getting a tech in 1 turn with 80%, u will still get it at 50% thus giving u 30% to spend on ships or planet production.
Good luck, GC 2 Is a great, great game and will continue to get better.