When you have "Players can see all systems" on at the game setup, do NOT choose Ancient Race as a racial trait
No, but seriously.
In stock SEIV, research troops quickly while still keeping an eye on other research, so your weapon/construction/whatever technology doesn't get too outdated. Once you have strong troops, create a couple of hundred (or thousand, if your economy allows) and load them on cargo bases in orbit/in a specific location like an obscuring storm or nebulae.
Here's something I always do:
Create bases with ONLY cargo storage (as soon as you've met the requirements for B/CQ/LS by placing those or MC) and build one/a few in orbit around your Homeworld. Then, whenever your population gets above a certain level, place a set number of pop on those stations. That way, you can have billions of people in orbital stations, even if you start on a Tiny world. The reson for this is that this way, when you colonize a new planet, you can immediately fill it up to max pop to speed up its growth tremendously while not emptying your HW this way. Also, when an important colony has suffered severe population losses, you can replenish the pop. Or, when an important colony has been depopulated with - what are those things called again? Neutron Bombs? you can immediately repopulate it completely so you get the full income again after just a few turns, instead of suffering perhaps crippling losses to your economy over the course of perhaps several years.
It pays to have decoy drones. They can draw fire away from, say, your heavy fighters. Seekers can also perform this task, and don't need to be produced. Make your drones contain nothing but a computer, engines, and armor, and set their strategy to something like Point Blank.
Do NOT underestimate the power of heavy fighters stored on a planet. I've had multiple occasions when, in strategic combat, my heavy orbital bombers were suddenly destroyed by massive streams of fighters from the surface of the planet.
Also, do NOT underestimate the sheer defensive power of a Large Weapons Platform design containing nothing but shields, regenerators and armor. Place a few of these on your planets and orbital bombers will have a hard time bombing as they're up against heavy regenerating shielding AND armor, while WPs keep pounding away at them from the surface.
It's always handy to have at least one WP on a planet full of long-range weapons like the WMG, while others are packed with heavy short-range weaponry. The WPs with the WMGs (or other heavy long-range weapons) can probably get off at least one shot at an enemy fleet before they can fire on you. If they're unshielded, it's even better - you can cause severe damage to their internal components, perhaps you could even eliminate crucial comps like the command comps, engines, heavy weapons or orbital weapons.