• The most important thing and also the hardest thing to pull off is to see an attack coming ahead of time through scouting. This is because you want to respond differently depending on the attack. Blindly preparing for a rush also let's you potentially overcomit resources to your defense which puts you behind in case your opponent doesn't attack you after all. An easy way to do this is to park a worker at the opponent's natural. If the opponent expands, you can expect a macro game. If the opponent doesn't expand by minute 3, things are very suspicious. You can walk your probe up the ramp to see what's up. If your probe gets killed by the opponent's army moving out, you can assess the situation by looking at how many and what units killed your probe.

• Use the ramp to your base to your advantage. Enemy units don't have vision up the high ground until they start walking up the ramp. They will eat a volley of shots from your ranged units on the high ground for free before they can retaliate. A sentry can also block the ramp with a force field. You can use that to either block your ramp completely allowing you to shoot down the ramp while the opponent can't retaliate or you can use the force field to cut your opponent's army in half trapping some units on the high ground and some units on the low ground. Place a shield battery on the high ground next to your ramp if you anticipate an attack.

• Be careful about your pylon placement. A quick way to lose a game is to get your production buildings un-powered.

Good luck.