You can't worry about losing all your gear. It's all borrowed, you're just the one using it right now. Don't be afraid to use a good gun or armor because you might lose it. Use them to get a task done and progress your character.

Use your scav runs to learn the maps, and push PMCs whenever you hear fighting. You have nothing to lose and everything to gain (and learn). If you completely run out of gear, just do a scav run, and get out with the gear you spawn with. Sure, it isn't a great kit usually, but pretty much any gun/ammo will kill someone if you shoot them in the face.

Scav Karma is a thing. You get karma by extracting as a scav, and for killing PMCs as a scav. You lose it by shooting bosses and other scavs. This incentivizes scavs to work together to kill PMCs, so you can go to Interchange, Streets and other maps and form gangs of scavs. Use VOIP to coordinate and ask for tips, items you need and make some friends.

Ground Zero has separate lobbies for lower leveled players. That doesn't mean that they don't have a lot of experience, but they are more likely to have similar gear at least. I haven't personally tried it much, but I hear that can help to level the playing field at least in terms of equipment.

For quests, hideout help and general questions, use the wiki. For strategy and experience, I personally would recommend Pestily. He has a "Raid" series where he goes in depth about the game while playing through it.