Don't stockpile mechs like crazy, you really only need 4 with maybe one backup. Don't be afraid to sell most things. Early on salvaging mechs can be hard because they tend to lose center torso and die before you can take 2 legs, or get enough wounds via side torso destruction + knockdowns or headshot. (You might find yourself needing to essentially reserve and juggle things that you can LRM boat them from 0 to full stability, then someone else hits with a minor thing to finish knockdown, then give your other mechs a chance to free called shot them on the ground, or if it's close to dead, let it stand back up and knockdown again...
AC'2s should be quickly outgrown. Try building boats min max style. IE 1-2 LRM boats. (Though again I'm not sure how nerfed they are since I finished before patch, but they should still be reliable damage) Then usually an SRM/MG boat was good. And iirc medium lasers still the hotness there so you can build a medium laser vomit build for murdering things you arnt trying to salvage. High heat mechs generally mix well with meleeing. Blow all the heat you can one round, next round punch while dropping heat.
I gave up on AC's unless I had no other options except for AC20's that were still great for called shotting to the torso to just delete medium/many heavies quickly.