One of the best additions to a fleet is a shipyard ship. If you keep one of these in each fleet you can retrofit your fleet while moving.
I generally have 10 - 12 ships in my battle fleets. Only 4 - 5 are combat ships the rest are support ships, flak ship, minesweepers, repair ships, etc.
My current game is on turn 250 or so and my fleets average 12 ships. My combat ship mix is 1 BB, 1 L. Carrier and 3 LC, the rest of my fleet are support ships. Have not lost a battle with this mix in well over 150 turns. You really don't need a large combat fleet is you support them well. About the only time you must start building up your combat fleet is in a high tech game or when your opponents have researched most of the available tech, turn 500 or so. Keep ahead of your opponents in combat techs and you will have a distinct advantage.
Keeping track of your ships can be difficult. I generally limit my designs to 2 beam ships and only 1 of any other type and oboslete they old design imediately after I redesign them. I prefer the direct approach to naming, my flak ships are call Flak Flak1 etc., my carriers are called Carriers. Not very original but it is easier for me this way. If you like exotic names and lots of designs you may need a scorecard to tell who the players are
[This message has been edited by Marty Ward (edited 28 April 2001).]