Had to make a new topic since for some odd reason all the other threads are archived, even ones from only a month ago.
First of all, I hate the fact that there's no tutorial or training in the game. I've gotten to the 5th mission, but I still don't know how anything works. I'm having problems maintaining an income now. I'm on the mission where you have 3 arnor ships, which cost like 180 bc, yet you start out only making around 60bc. What am I supposed to do to increase my profits? I thought maybe mining would increase the money you earn, but it doesn't seem to do that.
First, it's generally better to start with sandbox games in Galactic Civilizations. Most strategy games use the campaign as an extended tutorial to slowly introduce new units, capabilities, and opponents. GalCiv throws you in the deep end and assumes you know what you're doing, plus you're playing with an intentionally limited tech tree. Start a sandbox game on "cakewalk" to really explore the game; the AI is effectively brain dead at that level so you can learn with no competition. There should be tutorials accessible from the main menu, but that may have been the the original GC2 and not the expansions.
Trade: You can initiate trade with any civ you're not at war with by sending a freighter from one of your planets to one of theirs. The trade route will be established between the planet where the freighter was BUILT, regardless of any other planets you may send it to before using it to start a route. Trade routes vary in how much they are worth depending on how far along the route the mini freighter is, the distance between the planets, the age of the route, population on the end planets, economic starbases on the way, and probably other factors. As a rule, trade isn't available in the campaign missions, and is rarely an important income source anyway.
Tourism: This is based solely on the percentage of the map your influence covers. Another relatively minor source of income, but it can help with some "free" income at times.
Economic treaties: These represent cooperation between civilizations, and give the recipient 10% of the total income of the giver - without the giver losing anything. It's straight out money-out-of-nowhere. You do not have to have any particular relation level with a civ to get their econ treaty, but relations will affect how much they value it and in some situations it will be nearly impossible to get. Each civ can only give this treaty away to one other civ at a time, and only war between the two civs (or one civ's destruction) can end the treaty. You can receive as many as you can convince people to give to you. There is a pretty stiff diplomatic penalty if you declare war on a civ you have given the econ or research treaty to, but it doesn't apply if you are the recipient. Again not a huge income boost, unless the civ(s) giving you aid have huge economies.
Taxes: In most situations this is the biggest income source. It is dependant on your tax rate and population, as well as economic ability and structures on your planets. Expanding your empire by colonizing new planets or invading other people's planets will increase your population, as will building farms on your planets. Building economic buildings will allow you to get more money from teh same population and tax rate.
Be careful not to expand too fast, though. Each planet has upkeep costs associated with it, and these increase with how much has been built on the planet. New planets will be a net drain on your economy for many turns after they are colonized, until the population grows enough to make more money.
Population growth is based on approval, at the planet level. Base population growth is related to your population growth stat, which can be affected by use of start-up points, super ability, political party, passive bonuses from some techs, and a few buildings. At 100% approval your planet will grow at twice base growth rate, at or above 75% you get 1.25x growth, at or above 40% you get base growth. At or above 30% you get no growth, and below 30% you lose a percentage of your population each turn. Remember, this is the approval rate on each planet, not the aggregate approval you see in the bottom left corner of the main screen.
Check this for some additional information, or just keep asking questions. I don't check this as much any more, but if someone is active here I'll try to check more often.
He who laughs last, thinks fastest.