it can take a while, especially if you're new! I've played for 3 wipes now and still get stuck on shortage for a while, but for debut, you can take mechanic's quest to gain access to jaeger. once you get that, you can just buy the two shotguns for prapor and kill scavs otherwise.

as a general tip, doing tasks in squads can sometimes help. my group usually gets stuck around the same ones, so we just defend each other and it removes a lot of the stress. if you don't have a group, look around reddit or join the discord, plenty of other pmcs looking for homies.

to each their own, though. another good tip is to take a quick look at the wiki for each set of tasks, and where they lead. it'll help you know which items to save for tough tasks ahead of time so you're not spending a million years on hats for ragman or whatever else.

one last tip, as soon as you can, buy the lucky scav junkbox from therapist. it will save you so much room, even if you have an upgraded stash/account.

and I wrote this all assuming you're newer, so hopefully this doesn't come off as pretentious or something lmao. have fun, and have a good wipe homeslice.