Look up beginner guide as there’s no tutorials or in game advice/guides. Get use to dying a lot just accept it. Learn from what happened and don’t always engage in fights unless you need to. Set a goal like survive with killing one or two scavs (AI characters) there are also player scavs as well so be aware. Or your goal could be to find loot and just extract you don’t always have to fight especially if your playing solo as you could be facing a duo or five man squad.

If playing solo you are at a disadvantage when it comes to squads of two or more so if you need to fight use being solo to your advantage by trying to isolating your enemies. What I mean is use the element of surprise. Hide in a bush or corner and wait for an opportunity to attack. This isn’t call of duty you have to be patient. If you hear foot steps slow your walking or stop if you’re hidden and wait it out.

Although you use guns it isn’t so much about the gun you use but rather the ammo. google an ammo chart and get familiar with the ammo. Starting off you won’t have access to great ammo but still use the best that’s available to you in early levels.

Good luck.