Opening tactics...

[Suicide Junkie]

A good way to balance your development and your military is to have piles of Spaceyards.
You can then keep pumping out colony ships while you build your military.

With your homeworld, design and build 3 to 5 Bases with Spaceyards.
For other spaceyard planets, build a few orbital yards as well. Just keep an eye on your maintenance costs.

If maintenance gets too high, start mothballing the warships you create on the spot. These reserves will cost you nothing to maintain, and can be reactivated on one turn's notice for 25% of the build price, I believe.