Agreed, really think about your tactics.

Couple of tips that should help Goresh.

1) CARRIERS! Build these en masse. The best late game fleet you can have is a leveled titan, a leveled colonizer cap ship, and a leveled siege cap ship, with the rest solid carriers (seriously, don't build any more cap ships). Make only enough fighters to overcome the enemy's fighters, 25-30 is usually plenty, then go mass bombers. Leave the cap ships behind (they are vulnerable), and fly your titan into the enemy grav well, then fly your carriers in on the other side. Let your titan fight their fleet alone, and fly the carriers away from any hostile ships, while you manually tell the bombers to destroy key targets (cap ships first, titans second, starbases third). This requires at least 5 or 6 fleet supply upgrades, but once you've hit that, you can break any planet. Repeat, DO NOT use other types of ships. With this composition, you can retreat if you start to lose, and literally not lose any ships. 120-150+ bombers can shred pretty much anything in short order. When the enemy is dead, move the cap ships in to siege, and move on with the fleet.

2) Don't split your fleet. Build heavy duty starbases, and maybe a few carriers to defend your back, but don't split your fleet. You need it to overcome fortified planets. Once you've mauled one opponent, move on to the other. Build tons of tactical structures at the other side, but remember, they are just for slowing down the enemy. You will lose a planet or two on that side, but you need fleet to beat him, and it needs to be massed.

3) Be more aggressive. You need to be moving aggressively long before enemy culture starts pushing on you. Prioritize planets with lots of logisitics slots (desert, barren) so you will be able to put out more culture.

Hope that helps!

I usually play the Terran's (not rebels) For defending a choke point on large games, I build a star base (or two if deep into the game and complete the research). I max out the fighter, missile, and hull point slots. Just behind it I place another 4-6 fighter bays (all bombers) with defense module, a repair facility or two, and cannons (maxed levels with defensive missiles). Don't rule out minefields, they can channel the enemy where you want them to be (replace them when their lost). All these items need to be placed where they will do the most good, preferably between the jump point entry and the planet. A smaller force can hold off a much larger one easily. Usually 2 capital ships, and as many long range Javelin's as you can crank out. Resist the temptation to move into the enemy fleet, let them come to you. Keep your ships close to the star bases and repair facilities, they will repair as they fight slowing the damage they take.. Unless you're trying to build up a levels or are waiting for a star base to finish building, your wasting their awesome offensive capabilities. Star bases put out a massive amount of fire power if leveled up. Insure large enemy target are in a crossfire and force to spread their weapons among multiple targets. The enemy will usually concentrate on star bases and capital ships first, leaving smaller craft and defense platforms free to fire. Pause the game if you feel overwhelmed, need to issue lots of orders, or check other locations.

Offensively, if broadcast towers and culture creep are getting you, create a strike fleet, move it into the enemy gravity well right next to the broadcast and take it out, if opposition is very strong retreat. It's a good idea to have a decoy fleet strike another of the enemies planets, even if they can't do much damage. It will keep the AI guessing and might keep them from sending reinforcements. Coordination is key. The decoy fleet should arrive a minute or two before the real target is attacked, best case scenario pulling away enemy assets from the target, next best case, keeping the target from receiving help. In any case if it's bad, get out of there. Don't rule out pirate raids. They are a good diversion, and even better if you know their route of attack. Send a scout ship to the star (it often has the starlane to their home world) keep your distance and follow them to learn their path. Avoid taking planets along their route if possible, otherwise your ships will attack them, even if they aren't your target, while taking pot shots at you. You want them to arrive at the other player/IA target with their full strength.

The boarding party feature on the support capital ship is nice. You can pick up a few enemy ships to add to your fleet. I avoid the demolition ability, so they don't blow up the prize ships. When you defeat a fleet with a world or asteroid after a battle capture the planet, even if just to build a repair facility (that should be first). Have production from your ship building worlds move/rally at the newly captured gravity well . Think of it as island hopping in WWII. Repair, reinforce and press on, keeping the pressure on. As stated, carriers are great but weak on their own. A capital carrier ship is good as it has much more hit point and other abilities. Bombers/fighters are also great covering a retreat. they cost you nothing (as long as its carrier is safe) to make and replace. I rarely build siege frigates. They are weak against other ships, and a large fleet can take a world out relatively quickly. Repair ships can be brought in after the major battle, while mop up is taking place, to begin repairs until better structures can be completed. More than one enemy? Don't fight the enemy that isn't fighting you. It might seem logical to help the little guy against the stronger one. Problem is you'll most likely do all the fighting while he's rebuilding and researching. Depending on the big guy, the little guy might be your equal or better when his time comes. Clean up the easy picking first, let your capital ships level up and look ahead to plan good choke points to capture. Don't hold worthless systems or those that would be problematic defending. Better to raze them, let the enemy take them, then hit them from time to time and raze them again. let the enemy sink credits into holding bad real estate.