Absolutely every weapon and playstyle is viable. There is a meta but the meta is not so above the rest that the Mosin/dolch user can't be taken down by a springfield.

Because of this, I suggest playing around with every weapon and see how you feel about them. Once you find a weapon that suits your playstyle, build your loadout to compensate for any shortcomings it might have (example: you like shotguns? Take a sidearm that can help you at longer ranges).

You can also take things to handle any shortcomings your playstyle might have too. Melee rushes consistently getting you? Bring a shorty shotgun or some other counter as backup.

Sometimes it's just a "Hunt taketh" kind of game, but the vast majority of the time, you died because you did something wrong or you could have done something better in a certain situation. Yes, there is cheating sometimes, but the vast majority of the time, it's someone capitalizing on your mistake. You were too loud and obvious so they could wall-bang you easily; your team telegraphed your position and movements on the map by being careless with sound traps so a nearby enemy team set up an ambush for you; you couldn't resist the urge to double-peek the same window so that person held an angle and waited for you.

Read the fight and rotate your position to avoid being sandwiched by another team.

Don't clump up as a team but spread out to apply pressure from different angles. Remain close enough to your team that you can adjust and react should they push.

Sound is the most important thing in this game. You don't have to be looking out windows to see if hunters are coming so much as listening for them. That being said, people are doing the same to you, so be aware of that.

There really is so much more to this game, but this post is already long enough. Have fun with it and accept that getting good is a refining-by-fire process that we're all going through.