System taking
by Psilondude

Even the magnificent Psilon started off as a one-planet empire. Growing really big can be a really big problem late in the game, as all the planets are taken by avaricious AI. Some dumb AI even share systems between themselves. However, I have a solution. To circumvent this problem, it is better to grow early in the game. On your beginning planet, put all DEAs possible in towards Industry. Shift all production to Colony ships and butter other empires up. This will mean that while you are safe while you colonize systems, other empires will see you as not threatening. Later in the game if you wish to you can turn your back on them. To do that you will need a strong economy. Anyway, back to the main point. Expand early in the game when specials abound and systems are free. If you are at the start of an arm in an arm galaxy, you have a highly advantageous position because you can pen in that galactic arm and take it for yourself, and if you must, destroy the locals.

The whole overall point here is to colonise early and be friends early in the game, then switch to a dominating, militaristic view later.