Tactics are moment-to-moment decision making. Strategies are broad decisions about the course of the whole game. Principles, however, are decisions about what those other decisions are supposed to accomplish. Before playing the game, I identified eight principles that I thought I should follow to become a strong player. These are largely borrowed from other strategy games or in a couple of cases from military theory, and only the last is Zero-K specific. However, from my outside view, they seemed to be both significant and relevant, and my recent game experience has borne them out.
Inflation Metal spent now is worth more than metal spent later, and stored resources and idle or otherwise unproductive units are slowly losing their innate value.
Return on InvestmentAfter essential defensive spending, invest in things that will produce a profit in a short time. However, as the game progresses, the best options generally become bigger expenses with longer payback times.
Forward Unit ValueUnits in a position to do useful things are more valuable than identical units far from where they will be used. In other words, necessary travel time is a cost.
One Big Project RuleOne complete project is worth more than two half-complete projects. Don't attempt several minute-plus construction projects at once, pool your build power on one of them.
Nash DefenseDefensive investments should mitigate your weaknesses, not reinforce your strengths. The severity of a weakness depends both on how difficult a place is to defend and how harmful a successful attack on it would be.
Concentration of Force a.k.a. Lanchester's Square Law
In a pitched battle, units that fight together and support each other trade proportionally more efficiently than those same units fighting one at a time.
Frontage Limits a.k.a. Lanchester's Linear Law
When the enemy units are inaccurate and/or have splash damage, or your units block each others' attacks, your units trade less efficiently in proportion to how much attacks damage units other than the intended target. These effects can go so far as to negate the entire benefit from Lanchester's Square Law of adding extra units to your army. All these issues can be reduced somewhat by fighting over a wider front, so long as all your units can still attack.
Theory of VictoryGames are won by denying the enemy the ability to produce, either by defending every metal spot on the map simultaneously or by killing all their energy structures or build power. The former option is generally a more reliable endgame.
These eight principles aren't exhaustive, and I welcome more principles of the same significance. But they seem to form a good basis for all the other rules of thumb to build on. They all have their own rationale and corollaries, enough that each should be discussed separately lest I overwhelm my audience.
