Scorched earth P4 can one shot anything in a building with its incendiary shell.
When running into atgs make sure its the shortest path and try to be behind them
Sacrificing a p4 against an ab blob is usually a fair trade off.
If you got stickied chances are they just wasted 4 rifle squads.
And above all, learn when to use lock down and when not to.
Most importantly, vet is nice, but some of the best most rewarding moments were when i sacrificed it to kill large amounts of infantry with lockdown.