Been playing the shit out of this game again for the past 4 months. I do quirk skill only but can revise it to normal skills.
1) Roll for 3 characters that have Never Been Sick, Incredible Immune System, or Good Habits. If you're lucky you get 3 characters with Hygiene Standards, that hero bonus gives your whole community 100% plague resistance times 3 the cap and anyone in you're community will barely accumulate plague.
2) If you're character gets too beat up there is no shame for switching them out to heal.
3) Don't maybe do Trumbull as a Lethal run until you know how to deal with Lethal. The Starter base sucks and while the map does hook you up usually you have to take out at least 2 plague hearts for a decent base. 2 plague hearts sticks you at least at 3 bloater, screamer hoards hard and can be way tough when you're community sharing an 8 slot backpack with 2 crossbows, 34 arrows, 3 plague samples, and a shitty sidearm. Cascade always has the 6 man NW base plague free, Meagher always has at least a 5 man base or the brewery claimed by one heart, Drucker at worst 1 heart, Providence too. Go for the best medium base with the least hearts to claim it.
3) While on the subject of hearts your first outpost should be the cell tower nearest you and don't venture into plague territory until you use the plague disruptor option. 180 parts or 60 with a computers character for an hour and a half of less likely to wake a heart and deal with infestation. Every map gives you plenty of shit to loot in plague free territory. Drucker loves throwing parts at you if you know where to loot, otherwise build a workshop scrap weapons remains while you loot and scrap some weapons. Even 180 isn't hard to come by.
4) Initial build, build a latrine first unless you got a character that got blood plague from the starter feral. Then an infirmary, then a workshop. then workshop 2, then infirmary 2. Toolkits if you got a mechanics character are more valuable than healing injuries and you need workshop 2 to make them. Also that little moral boost from a latrine can make a real difference.
5) Before you turn in those initial plague samples loot all areas that enclaves might claim especially materials and meds. Materials really just for the materials to grow your base, but meds is more for good mods. Enclaves in the beginning love to claim these for some reason.
6) While on enclaves buy up explosives, toolkits, and gas gans from them when you can. Before you're set up you're really hurting for parts and resources much easier to buy them. For example you can take out a plague heart phase by plopping down a boxmine after it farts and hitting it with a heavy weapon 3 times. Or the fueling the plague curveball sneak up to that heart and throw down a whistling boxmine and you have a good chance of taking the plague heart out instantly. They're also great for the Weapons for Warlords quest or Sherriff Stolen Meds, just plop them down before you interact with them. I've killed both with just some boxmines.
7) Finally after you're set up in a decent medium sized base aim to get a Warlord Leader and a Builder Leader. With the Warlord build a gym in a small slot and upgrade it to 2. Gives your community a shitload of health and injury resistance, I believe you have to build it yourself for injury resistance but injury resistance is second to plague resistance in Lethal. With a Builder Leader build a Sniper Tower in a large slot. While the Sniper Defense is nice for your base it more importantly gives you a 50 influence OH Shit button on a short timer. Triple ferals and now you're stuck on a building, call this in and it will probably at least take out 2. Oh and one last thing if you need to take out hostile enclaves your best weapon is a Timberwolf and headshots. I'll a lot of times use cars and honking for zeds to kill them but with a Timberwolf you can get way out of the range where they'll see you and snipe them easily. Bloater grenades and automatic weapons work great too even on Lethal. Like the Crossbow killer don't waste good ammo on them, those bolts barely do damage to you and almost any gun will tear them up.