Its simple. All you need is 3 bunkers full of marines and 6 SCVs on repair duty at your choke point. Of course, it would be nice to block it with something. To accomplish this, start producing your Barracks at 7/10. After you got your defense up, the first building you should produce after your Barracks, Supply and Bunkers should be your Ebay. 1 missle turret at your choke will provide adequate protection against invisible units. After that, build an academy, factory, starport, etc. When you expand to another base with your dropship, go to a remote place like in the center of the map of Wheel of War or something or to an island without a ramp on Frozen Sea. Be sure to bring along a couple Siege Tanks with siege mode, even place a couple at your choke. After that, build a couple medics for restoration purposes at your choke. And then get an armory or 2 for goliaths. In the end, after you've defended and expanded, you can simply destroy the computer with a force of Siege Tanks/Goliaths, or BattleCruisers, nukes, or a mix. I find the best is a mix, but the computer always falls for nukes and are fun to use. Enjoy. I never use this strat against people. People will not stupidly suicide units on your choke. People are smart. Against people, I usually will do a simple rush defense followed by an aggressive attack, coordinated between me and my ally.

CreepColony's Opinion: Hotkeying your SCVs might help.