I have been reading this thread with interest, and thought I would inject some of my own pbw thoughts (hopefully I don't intrude too much).
1: Weapon choices: VERY important, watch out for Engine Overloading Weapons, can be deadly!! (I always use them, very good against those who rely on short ranged weapons such as null-space). Don't rely on PPB too much, players develop Phased Shields earlier than the AI, APB almost seems a better choice (more range).
2: Armor: Definite must, stealth armor can decide a game early.
3: planet busting weapons: Plague bombs and such, good but watch out, using plagues seems to get everyone in a tizzy!
4: Shipyards! I tend to have one on almost every planet! (and watch out that you don't have only one Space Port per system, if it gets knocked out you could lose resources fast, getting half your fleet scrapped!!).
5: Planet/atmosphere type & Racial abilities. Very important to choose the right mix. I usually go for rock or Ice with none for atmosphere, moons everywhere!!, but Gas has min size of medium so they are good as well. If you do go for rock/ice none then the racial bonus for more storage/facilities is a must!!
Anyway, hope I havn't rambled too much, and hope I provided some points to ponder....if not just ignore and continue

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"And what the hell would you know about sanity?" demanded Beatrice. "There are depressed lemmings on the edge of cliffs who've got a better grasp on reality than you have. And more common sense."--Simon R. Green 'Deathstalker Rebellion'.
"We are all...the sum of our scars"....(paraphrased) Matt. R. Stover-'Blade of Tyshalle'.