Okay, once you have reasonable defense, if you haven't already, get 2 armorys. Get 3 more factories as well and start pumping Goliaths. Upgrade at your armories and at the machine shop. Get a starport, and then a science facility/covert ops. Keep making goliaths! Make 2 science vessels and 6 ghosts with lockdown/cloak/ocualar implants. Once you hit the supply limit, attack. The ghosts will keep away all pesky mechanical things such as reavers and tanks which are a huge problem.

CreepColony's Opinion: Ghosts might be a little hard to control, and they'll probably die pretty quickly so try to cloak and defense matrix them.