ok, my take on egin's situation. 2 bad i have yet 2 receive my copy of the game.:(
once arriving at the scene, do u have enough to pump out at least 4 squadrons of interceptors & 4 of bombers? if u can, do so. it'll be your inital defense & at the same time(i'm sure u know this map quite well by now to know where to harvest) send out 2 RCs (resource collectors) & one harvester (i forgot the name of that one) to a nearest harvestable asteroid clump while building another 2 to replace the ones u send out.
upgrade interceptors & bombers while building them. have your mothership build 4 corvettes of both types (gunship & pulsar) & if u have a carrier that can produce frigates, build 2 of each types (starting with flak & then torpedo with ion as last). once u have enough RUs, build another carrier to beef your offsite harvesting. oh yes, doesn't hurt to send a probe or two 2 check things out. make sure they're not to close to the action(just put them high/low on the Y-axis) or that 150 RUs down the blackhole.
keep pumping out units.
DAD's idea on having harassing force to kill the beacon & teleporter is nice. make sure u have a balance of everything. better yet, have a carrier with them.
u have to expand really fast by having multiple harvesting sites. so long as u don't run ou of RUs, u don't run out of options.