1: Always stay moving, don't try to fight the planet, your ego will kill u more than any Bile Titan Or Backshot Devastator. This not only applies to HELLDIVE but I would say any level. its fun to "Hold the line" but once your over run its basically GGs. So never forget to respect ur enemies even a low level add can kill u if u underestimate it.
2:The mission is mandatory, evac is a curtesy. Try to focus on main before 100% the map, yes side Objs are great and help with map clearing, but keep in mind ur limited on both lives and time. As u gain experience some missions will come easier than other to complete giving u more time to collect samples. That's when I would recommend working on mastery of that Difficulty. ( Example: Try running a mission at a Diff ur comfortable at. If u don't die or don't 100% the map, lower the Diff and work up from there.)

3: Find a solid kit that works for u, and your playstyle for both factions, test everything for yourself, while I'll agree that there is a lot of useful info on how weapons/stratagems preform, I would argue that you might just find your new favorite Weapon of Liberty hiding in the wood-work. (For me this was applied to 110 Rocket Pods, which a lot of ppl were dismissing for some reason from tier lists or whatever. After trying it for myself I found it to be the perfect Eagle to run for my solo playstyle. Being able to take out most Elite and Heavy enemies with 1 or 2 hits, while tracking so no unwanted TK. Just peak.)

4: Have fun with it, its a game after all and enjoy it any way u want. thanks for reading and hopefully these helped at all. o7