My strategy is as follows for any freeform map:
Tech up to max lasers
Tech up to Dreadnoughts
Get shit wrecked by Von Neumann (Like fucking clockwork.) (If it's not VN, it's some other form of SotS HFS.)
Get insanely paranoid and build a military force to end all military forces
Get attacked by alien race
Epic win follows
Get truce made to me because I'm fucking awesome
Deny
Expand like crazy
Locate alien homeworld
Fuck shit up with my dreadnoughts.
Repeat the last 7 steps until EVERYONE ELSE IS DEAD.
A dreadnaught only armed with X-rays destroying entire empires, wow....I got to try that
Hidden step between steps 4 and 5: Ultimate Tech Boom.
Usually involving Emitter tech, awesomelaser tech (By awesomelaser I mean the massive Spinal Mount lasers, and by Spinal Mount lasers I mean the mid-late game "Fuck your shit, you're dead." techs.) and the epic of epics, The dreadnought + HCL tech human-only combo commonly known the SWORD OF THE STARS (insert TVTropes Link here), or as I like to call it the "Middle Finger Of Win".
Also, I hate hivers because their ships are SO FUCKING SLOW without gates.
Also also, The random-tech tree system can go eat a dick. Whenever I want them, those helpful little techs like Mass Drivers, Graviton Beams or cloaking seem to be mysteriously absent from the tech tree.