[Klebdog]

I usually develop a Cruiser size ship with a shipyard on it and then build a Battle Station at two or three choke points throughout my Empire. These points act as a Last defense for for your core worlds, obviously you will eventually spread out past these points. The Battle Station is equiped with the latest Sensors Etc. and at least 1 Repair bay. I usually use 3 Null Space Cannons, grouped with 3-5 Beam weapons (Usually PPB), 5 PDC and whatever else suits your tastes. Make sure you have something to detect cloaked ships.
Make sure that your Stationis on YOUR side of the warp point, that way the AI will constantly fall into the same trap without changing their tactics. A human opponent will obviously change their tactics to face this obstacle, but you will have the first move everytime the enemy comes through the warp point. Additionally they will be right next to your station so range is not an issue, they will feel the full brunt of your weapons up close and personal.
Obviously you can reinforce these stations with small fleets or other stations or whatever you prefer, but I have'nt lost a station yet (except when I used a Space Station size) I once built a Fortress size one at a particulary contested sight and it held time and time again. I kept a Ship Yard ship close at hand to upgrade when needed and to help repair after big battles. Plus if you make it part of a fleet when ships come by they will refuel and continue on their mission.
This is just a tactic I use regularly with good success, feel free to take it or leave it.