loss of all planets under your control with no surviving allies

If your new, I'd try larger maps, they give you more time to build up your empire before you have to face an actual enemy, Aereolian Sector with all but one AI disabled should be perfect, and because it's such a large map, definately have all the game speeds at max.  I think it's a great way to get a feel for tactics and what research subjects and investments are most bennificial.  Keep in mind though that the tactics which work best in a large map won't help much in the small ones, when your on the small ones you best bet is to conquer as many planets as quickly as possible, and, in my opinion, avoid dumping too much money into developement.

Never played small or large maps against the AI. Large takes too long, in small I suppose you have to put up military labs, and build fleets&defenses so you can fight back. I played bigger small maps and smaller mediums, and easy & medium AI were easy to beat.

Load up on clues and tips on how to play. If you really lose to a single easy AI you are doing something horribly wrong.

Remember the Pause feature - confusingly mapped to the Pause key! Use this to buy all the thinking time you ever need when eg. deciding what to research next.

...motherfuck that really is confusing, I thought it didn't have a pause feature, I tried space bar, I tried esc, I couldn't find it in the key bindings, eventually I just gave up and would open the options screen, which is a real pain cause you can't see anything.

oh snap i never thought of that..