I've got over 1200 hrs in this game now and still die a lot. This game is not entirely about gear (although it does help) you can drop geared players with just a pistol, which i have several times.
I believe there was talk of a single player or story led campaign when the game is finally released.
Best advice - do the quests and get to level 10 quickly (flea market), upgrade the hideout as well esp for items required for quests.
Use your scav to rat a lot, the best way to get good gear is to play shoreline wait until the end of the raid (last 10 mins) then go to the East wing ground floor. There will often be several well geared dead players and raiders (if your lucky), ive had scav runs doing this where i literally couldnt take all the loot.