I'm still fairly new (not necessarily in terms of time, but in terms of number of games played), and I find that one of my biggest problems is figuring out the following two things:
a) What do I need to destroy (and keep alive) to win the game?
b) What can I destroy with a certain commitment of units?
Both of those are basically a matter of doing some rough maths (be it points or damage), and it's not even that I'm particularly bad at maths – I just never seem to think to do it, and sort of wing it instead.
What ends up happening when it comes to a) is that I make bad late game decisions regarding whether or not to commit to finishing an enemy off, or whether to disengage with a certain ship or keep it in the fight, because I'm not aware of the current score and how exactly losing/killing a given ship will impact it.
What ends up happening with b) is that I commit either too many or too few units to destroying a target. Last game I played I was flying Cracken MSU against an ISD+Interdictor, and I threw a bunch of ships at the Dic because I figured "Interdictors are super tanky". Turns out I blew it up much quicker than I thought (with pretty average rolls, I'd say), and suddenly I had two unactivated Hammerheads pointing at empty space with nothing useful to do for the rest of the game. (In that particular example I probably couldn't have taken down the ISD anyway, but it serves well enough to illustrate what I mean.) Other times I've realised halfway through an ISD that there's no way it's going down and I've wasted a lot of firepower that could have gone elsewhere.
So yeah. I imagine that sort of stuff will become more instinctive with more games under my belt. Still, doing some rough maths during the game probably wouldn't hurt – but when I'm actually playing, it doesn't seem to even cross my mind. I just sort of do stuff.
Edited by VillakarvarouskuWow, that's way more text than I thought it was