Depends on your tactics.
I usually build one tractor turret on each wormhole for starters and then work it from there with mobile forces set on FRD. I usually tech straight for bombers, and thus building MK3s, along with quick starships. Groups of five basic turrets over each wormhole also help a bit, but early game I'm mainly focusing on expanding, using that extra crystal to build forcefields over my quick expansions, and then start to develop my fleet and defenses afterward.