I just completed a second playthrough on Expert so here's my advice on how to have a relatively smooth experience.
-Dump ALL of your XP into maxing out Evasion. Minimizing damage to your star is paramount and it will potentially leave you with more resources if you aren't having to recruit more technicians and upgrade the repair facility all the time.
-Upgrade the science lab and recruit more scientists aggressively. Spend most of your merits (blue currency) on this, keeping just enough merits in reserve to unlock a new chassis when it becomes available. Max out the amount of salvage you can take early.
-Upgrade armor first.
-Upgrade heat sinking capability and capacity.
-Selectively upgrade the weapons you're leaning on. For me that was ER lasers and PPCs.
-Skip out on unlocking the Adder, Gargoyle, and maybe Executioner. It'll save you valuable merits, especially early on to skip some 'mechs.
-Spend your 'mech XP on unlocking the better alternate configs FIRST.
-After you've got the alternate configs unlocked and customized, spending that extra 'mech XP on maximum speed, acceleration/deacceleration, torso twist speed, etc is in my view worth the time. Your 'mechs will handle better and every little bit of extra speed helps on those big slow assault 'mechs.
-When customizing, make use of extra armor plating, especially on the arms.
-Optimize the ENTIRE STAR. Everyone should be in a tweaked custom 'mech with a focused weapons loadout. No stock configs.
-Pay attention to the finer nuances of how salvage works. You can tweak which components you're taking home from each mission to suit what you need.
-Use group fire to hammer 'mechs, chainfire to destroy VTOLs and turrets.
-Order your entire star to focus fire on SOKOL engines and dropship turrets to take them out quickly.
-Make a general habit out of ganging up on individual 'mechs with your entire unit. Worth it to put down an enemy fast even if it means ignoring his buddies for a few seconds.
-Keep an eye on your star and make sure no one has gotten stuck somewhere. There's 4 of them, it can be surprisingly easy to lose track of where they all are during these intense firefights.
As far as general gameplay tactics, I've been running long-range configurations in Mechwarrior for close to 30 years now. It's been my general experience that having your entire star outfitted to start shooting the very second something appears on radar is essential to pick off small enemies and begin the process of attrition on the bigger ones as early as possible. The ability to perform headshots on ANY enemy 'mech means that with some skill and finesse you can potentially one-shot a lot of serious threats before they can even fire. At the very least, by the time they close in you will already have slagged a significant amount of their armor. For me, getting in those regular headshots was pretty essential to end fights quick and minimize the damage we suffered. By the late game every 'mech in my star was primarily armed with ER-PPCs and gauss rifles, with maybe an LRM system or set of ER large lasers here and there. No one had autocannons, SRMs, or pulse lasers. Not saying that other builds aren't valid, but for me at least this was a pretty effective setup.
With PPCs, I just have to manage heat and I can chain fire them to smack all those pesky VTOLs outta the air from extreme range. My advice in all the Mechwarrior games is to eliminate the smaller enemies as fast as possible so your friendly AIs will have less targets to choose from. You really do not want to be overwhelmed, that's what will lose you missions.
While the developer put a lot of work into a top-down screen for ordering starmates around, even on Expert I was basically just commanding them to focus fire 99% of the time. Especially in the late game, it's pretty much a matter of pounding the closest enemy into scrap then immediately targeting the next enemy. If the game actually PAUSED when you started issuing orders the nuances of that system would've gotten more of a work-out.
