Kalimar, what're your problems?
Main rules: expand fast, build fleet which serves it's best role and evade conflicts until you are good at them.
There're a few tips for a beginner:
1) Specialize your planets. Have at least one "scientific planet" with a lot of researchers, a "food production" planet, a "construction" planet and various resource-gathering planets. Also you may want a few "breeding" planets to send more colonists to new inhabited planets.
2) Make use of local population. If you encounter a planet with some native races, they can be quite handy.
3) Know racial strengths/weaknesses. In the race creation menu check their traits.
4) Note that more difficulty you setup, more additional traits computer gains.
5) Oh, almost forgot it: always have enough freighters.
6) Upgrade your fleet. Use as good weapons as you can but consider ship costs to be allowed to build enough. 4 mediocre ships is beter than a single "a bit better". However 8 scrap ships are worse than 3 elite ships with cool weapons.
7) Remember the previous post, but always have some decent defence. Even if you know that you're going to finish some cool research soon make sure you have some defensive force to prevent enemy blockade.
About research: focus on research techs at first abit (something with supercomputers etc.) to efficiently increase your scientific output. Don't always beeline for something single but also don't spread out too much, set up some goals (i.e. shield 3 ships with interceptors or faster engine kamikaze ships with troop pods covered by some point blank shot ships etc.).
9) There're a lot of other tips, you're free to ask and I haven't played for a few years so I start to forget.
9) Don't play elerians or any custom race with "feudal" trait. It's terrible.
10) A little "cheat" from me: make scout(smallest size, I forgot the name)+battle pod(more space)+interceptor ships at first. Thus you get 2 effective ships in the place of one, and at that time of the game enemy usually have some bulky ships with nice hp but not very good weapons and maybe rockets. So the battle starts, your scouts send out interceptors and start to evade enemy ships for all costs. Enemy ships try to get your scouts, usually they ignore interceptors and soon they retreat or become pincussioned by interceptors. This little trick really works.
Good luck, I love Moo2 and I like to play it with my friends, it's always cool to start as something omniscient and start to make them nasty surprizes
. However sometimes I am not that evil. Just usual "colony ships hunters" stealth cruisers.