These must be kept in the back of your base, away from a direct path from the enemy. Although your first Tesla Reactor or Power Plant probably will be placed up front to be near your first structures, place later ones well behind your other buildings. Your power supply is vital to the health of your base because most of your base defenses rely on it. Keep them behind your other structures so enemies can't target them. Although your units are initially more effective base defense than structures, you need to have base defenses.
Air defense is a top priority, particularly in later missions.
You need to have Flak Cannons or Patriot Missiles everywhere in your base to prevent enemy attacks. Same goes if your playing in skirmish mode or against a human player online. One of the most important basic strategies to help ensure victory whether you're playing as the Allies or the Soviets is attacking enemy miners. This is just one aspect of attacking that will help you succeed. In every mission, for both the Allies and the Soviets, you can't win without attacking some point.