Good points! Okay, here's my first try at helping someone here:
Since you can't do anything without money, and percentages early mean lots of money later, I don't skimp on the research for trading, or even population increases or crystal/metal increases, especially if I'm low in one or the other because all of the nearest planets are all desert or all ice.
I like a high percentage of cap ships to fleet ratio. That is, I will upgrade my fleet in terms of capitol ships first before increasing overall level (and thus adding to fleet costs). I avoid raising fleet costs for as long as possible, usually after I've completed the first two to three tiers of research ("best of" on both military and civil) and snared trading income. And I will buy the planet logistics upgrades in order to do so.
I try not to increase fleet percentage to 38% until I've got at least 5-6 good planets, but this is not always possible when there are a lot of phase lanes. I don't increase to 9% cost until I have 2 capital ships and need a third and have at least my homeworld, home asteroid, preferably two other planets and trading, but with 4 players that isn't always possible, especially if one of them is hard/aggressive. It's best to learn with all opponents normal or easy, and only one aggressive, the rest researchers or economists. Then when you compare your graphs with theirs you know how you compared. Between an aggressive, researcher and economist, I like to be the line that is in the middle on most things, or better on income and equal on fleet.
It goes a little like this:
Upgrade planet's pop fully. There's no income until you do.
Use the black market to buy about 200 in crystals, you'll need them right away. Buy when you need as long as they're cheaper than 350. When you have extras, place them on the market to sell to other players at the good price. You can get it back by right-clicking if no one buys and you suddenly need them.
Place all crystal/mineral extractors. Again, no income until you do, but even if you do, no income until the planet's upgraded.
Build two scouts. Yes, two. Use direct commands (click then shift-click) to find out what all your closest planets are, with both ending at your home for new instructions, or ending up at the outermost-planet and going on automatically. Toggle OFF the automatic wander around the universe option for now on at least one of them, get intel on only the closest as fast as you can.
Build capital ship factory. It's a fast build.
Pick capital ship with colonizing ability. It's one less thing to worry about. As far as I know, bombs go farther, and they're definitely better on planets and structures, so I usually pick my squadrons to be heavier in bombers than fighters and dock them right away. Work on creating discrete (seperate) fleets with a good combination of two or three capital ships. Don't choose every ability, only choose two and upgrade them as your ability points acrue. Otherwise they eat up too much antimatter and your ship is a sitting duck for too long. It's really painful to lose an experienced capital ship! You can pick two of the same with great battle abilities, pick two of the four abilities on one and the other two on the other, then pick a second type of capital ship that is mostly a supporter (Advent really needs the shield help, it's easier to shield them than make them more battle-worty).
Pick logistics. If your asteroid doesn't have any phase lanes but towards your own home world, take full advantage of the fact that it's isolated and unassailable - load it up with moneymaking rather than war machines. Satellites for research, trading. Try to do one civil and one military right away.
Buy cheapest (in terms of metal/crystals), easy-access frigates and the best one you can get (in terms of hull strength if in doubt, or not too particular about what it fires at) at about a 3 to 1 ratio. (Mid-game when you're taking over planets that are owned and not neutral is the time to get some planet bombers.)
Don't spend all your money or use up all your fleet points yet, becuase you're going to colonize your asteroid next, just as soon as you have a capital ship and at least 4-6 frigates. If, alas, there's a fleet there, do the math - if their hull points greatly add up to more than your hull points, let them battle it out until your capital ship has most of the shield gone and retreat. Once you acquire the asteroid, upgrade it and install extractors, choose logistics and military, visit research if you bought a research satellite and have cash/crystal.
Tip: When creating fleets, be sure and turn off the auto-join unless you really want it to suck up every other ship around and risk losing a ship that was being repaired or a scout/colonizer that was waiting for orders. I find standard or loose works best. Tight tends to only work well when you have two or three fleets and can maneuver them to encircle and entrap the enemy, but I could be wrong. I don't always micromanage battles.
Next time you have the funds, put it into research. Buy whatever's in the first level that will do you the most good based on what you know now (all nearest planets are ice, perhaps.) Anything that increases your planet's population (make sure it's a type of planet you own) or output of whatever mineral you're short in, or will be short in (count asteroids closest). Get the military ones that are always good no matter what. (Repair platform, hangers, hull strength, shield strength...). Next objective is right to trading posts.
Come back to the research page whenever you're:
ahead in money and fleet is fully built up. Money sitting around does you no good, unless you're earmarking it for a capital ship.
have just constructed a new civil or military research center, new things are unlocked.
are getting killed and need ships that last longer.
If TEC, the different ships that you have to research for are for most part a luxury, you don't really need all of them except for looks, thrilling battle scenes, so save them for your third or fourth army/hostile takeover. The LRM is worth it.
Keep an eye on the pirates. If it's cheap enough, buy them off. If it's not, heck, they're pretty easy to kill and outnumber and it will rank up your experience.
The first third of the game, don't give anyone your crystal or metal. Credits maybe.
AI rarely says okay to anything but trade. I've gotten very friendly with them and they still say no. So don't waste your funds. What IS fun to do is to play a game as an ally and then declaring war on them after you've killed everyone else. Bout the only way to win as Advent is to ally with an Advent AI. It's a fun way to play actually, you get to see -- from the start -- everything they know about ships and planets, so half the galaxy is discovered before your scout ships have even made it to the fourth planet. And they'll fight the pirates with you.
The more phase lanes, the tougher to defend. When in doubt of which planet to go for next, or which map to choose/design, as a beginner go for the one with the fewest phase lanes. If you haven't researched for faster travel yet, always pick the closest no matter if it has crystal and you already have more crystal than metal. Buying back planets you once owned is a major pain. Keep what you get. I wouldn't play Advent on a map with a lot of phase lanes unless I was allied. So far on a medium custom map I've captured nine planets, lost one, as Advent, and my fleet is still at a measly 38% of income. Woo hoo!
This much always works well for me. The rest depends on the type of map and enemies, and which empire I'm playing. When playing TEC against TEC I tend to build up my fleet more, buying more metal from the black market than crystal.
Hope that helps!
ShelleyCat