for me, I always play in 100 planets and a 1 star map (multiple star systems seem inorganic, and they dont appear to generate fairly. additionally it softens gameplay, making it too easy to turtle. you sissy kosc

)
I usually play by initially making small groups of scout frigs which wipe out pirates, capture as many planets as initially possible, and stage light defensive structures at dead asteroids (which are almost always at strategic loci) or big junctures/choke points.
usually upon first encounter with an enemy I lose a planet or two, but the initially "boom" phase allows me to quickly create a retalitary force which can survive and woop butt.
my military strategy includes the creation of numerous initially small fleets, of which I later consolidate and place at strategic loci after the initial boom phase subsides. smaller fleets are used to expand. any money not going into infrastructure, replacement of destroyed ships and
light fleet enhancement goes into research, my tree is usually maxed out within the first 30-60 minutes of the game, after which focus falls on maintaining an economy and creating new ships to amplify my fleets.
strategically most offensive/defensive weaponry is placed on outskirting planets, preferably dead asteroids where little collateral damage is likely. the result is that I'm usually able to rebuff any attack my enemy sends at me.
weaknesses in my strategy include: fleets are usually too far away from one another to assist each other, initial military strength is weak, forces are widespread. high risk of losing KOL early on.
strengths in my strategy include: fleets are usually capable of holding their own post-initial, I have access to powerful units faster than most people, economy is almost always able to outcompete my enemy, I have a deathgrip over key defensive points, enemy has not been able to penetrate my forces as of yet. I essentially get first dibbs on essential key locations and planets, and many times this is the difference between surviving, and kicking [colloquialism for anus]