Fleets should be made up with a mix of your fighter carriers and have a SSF or better mine laying ship with it. Remember that you will have knowledge of the area you are assaulting prior to your offensive by using your probes for darksense info. An ally that follows thru on plans made by the alliance and keeps his part of the alliance up is worth his weight in mega credits. Combined with communication is the exploitation of the add-ons that are in use in the game. In order to win you must use all the technology available to you.
Probes make alliances feasible even over vast distances.
Give your ally a probe and he can HYP into your area and take control of a Starbase that you give him and build ships for you. Of course, he must reciprocate for this to be effective. Build tech 1 Gorbies and have your Fed ally refit them for you. Although there are a lot of variables involved with battle, one of the keys to winning is following up with a strong fleet of freighters to take max advantage of any territory gained. There is no loss of honor in falling back to regroup, but you must have a plan to use or a strategic retreat can suddenly turn into a route.