I had been tempted to get this for a long long time after seeing a few FPS streamers play it a year or so ago, finally did over the holidays because I had fuckall else to do the week of new years.
On the game itself -- ammo is more important than the gun shooting it. Did a few offline raids on Reserve just to test ammo against raiders since they often run high level armor/helmets. If you run non armor piercing armor you better shoot them in the face and hope they don't have face shields, otherwise you will get buttfucked. Same thing against players but depending on the map it could be more CQB and helmets aren't as important, ie labs or factory. Running shitty rifle ammo (ie PS for AK's or M855 for AR's) might be fine against scavs but any decent body armor will tank the fuck out of it whereas the big dick ammo (7N39 for AK and M995 for AR) will drop people very very quick with a good chest burst.
As a scav I've primarily stuck to running Reserve and literally scavenging bodies of raiders for gear to sell/horde. I've come out with 500k+ worth of shit before in a single run assuming I can find (or spawn with) a decent size backpack. Built up a fat stash of armor and weapons without spending any money. PMC runs for me are rare, I don't know Shoreline or Interchange at all yet and I loathe Customs. Reserve not a fan of the extracts, wouldn't be as big of a deal if I had a pick to use the mountain extract but I'm too poor to buy one. Factory I also need to learn better before I bring good gear in, and for the love of fuck do not ever spawn there at night unless you have NVG's. Pitch fucking black and scavs will rape you in the dark. Made that mistake once, never again. Woods haven't messed with it yet, same with labs. Every time I find/spawn with a labs keycard on a scav I die, never fails.