If you are like me, you would rather play against AI or play PvAI matches rather than against other players (although in my case this mostly applies for RTS games)
Anyways, I have found that the hit and run tactics of the AI are rather annoying and tiresome. To remedy this I found a little tactic which I like to call "stepping on their toes" For booming players such as myself (and turtlers) I find this a complete bane.
We all know 99% of the time if you outmatch an AI's fleet by numbers, or tactics they will run away... Personally I hate this, but have found a way to draw them out and make things a whole lot easier.
What you need to do is send your fleets to the closest planet they have near your boarders. Leaving your ships in this area razing structures and whatnot will cause the AI to send in their fleet eventually so you may finally rip them apart. They may run away if you give them a really good pounding but don't chase them. Just continue your assault on the planet. When that it done, you should immideatley colonise it and move your ships to their next colonised planet.
You may loose your recently achieved planet (or one of your rear planets) to their lame "bombardment fleet x50 hit & run" or flanking tactics, but that is OK, you can recolonise it immideatley after or just wait until its safe to recolonise, if you are tired of losing funds to upgrading it and adding defenses.
Anyways, just keep on stepping on their toes, bomb & colonise their planets one after another only spending money on upgrading the pop infastructure to prevent money loss. Remember, to try to keep your fleet in their territory as much as possible. This is what this tactic is all about.
As a personal perfrence if I find a desert planet I will stop there and fortify it and make it a forward outpost for reinforcements, then continue my push. This usually consists of 4x frig factories, 1x capital factory, 1x repair platform, 4-5x hangar bays (bombers), and however many defense turrets you can spam.
On huge 10 player, 102 planet maps, and unlocked teams, this tactic is very hard to do and requires at least 3 huge well put together fleets. It may take a while to keep all those backstabbers at bay, but with skill, help from pirates, and some luck you will turn out on top eventually. I hope this helps those people who play AI and PvAI matches online. 
