Don't engage the enemy when you're outnumbered. Regroup before going back into the fray.
Don't keep your target selection on your cloaked teammate. The opponents can see his distance from them on the Target-Of-Target HUD element, and they will gleefully close in on him and hit him with an AoE.
If there are five enemy Defiants (or any other non- Galaxy ships) around you and you are AMSed - hit the galaxy button near your map and que again. Perhaps you will have more luck and fight against someone without P2W consoles. Extension of this - don't que for FvK until you are Klink and you'll save a year of your GPU lifetime. Otherwise spam will kill it faster then you imagine.
Don't bother with manual shield balancing if you are fighting cannon armed escort. It won't do anything so you may spare your keyboard (or mouse).