Get good...?

No, but seriously. Here is a guide about most things in the game... This post will not include legacy so find it out yourself legacy players.

Basically, it's just Decaying Winter, duh.

Shoving and parrying are pretty much the same, I mean, maybe not the timings.

But to parry... Press R. Parry whenever you get close to an enemy, and if it doesn't make a sound, press R again after you stop the first parry.

You are at a great advantage in this game because of how it's made. Your shoves are very powerful but your stamina regen is much slower than in Decaying Winter. You need every part of combat to be 'good' at this game. Learn your timings.

Okay, but how do I learn these 'timings'?

Sandbox exists. Just get like, GM and practice. It's slow, but it's better than dying, over, and over, and over again. Obviously, it might not be as effective to you as to others. Learn at your pace.

How do I tell when an enemy is about to recover?

That's the neat part, you don't. I was considering adding indicators (I might add it as an assist setting), e.g. adding Z's from their stun icon, but you already have a pretty big advantage.

How do I master shoving?

Use the dagger equipment. Yes, I am serious. It'll probably contribute to... not a lot, but it's good support, and definitely better than masks. Obviously, it only does damage when it stuns the enemy directly. 

How do I use guns more efficiently?

Use the First Shot Accuracy mechanic, where if you wait ~2-3 seconds (depends on weapon), you get no recoil for that shot. Breacher Kit does not have FSA, but one pellet goes to your cursor per shot, without cooldown.

Professional is very useful, so you won't miss as much bullets during sustained fire.

How do I loot better?

Unloaded guns don't have a mag in them visually. Loaded guns with any amount of ammo do, except for SLEG 2L, which only shows if it has full ammo, and it isn't very visible. And full ammo bags have an extra pouch, do note that ammo pouch multipliers don't affect this threshold. Scavenger's movement speed and scrapping gives you a big advantage.

What are recommended traits?

Professional, survivor, and literally anything else. That's the general playstyle, however, and it may not work for you, especially if you use a niche playstyle.

What is the best perk?

Soldier or scavenger. Soldier gives a lot of gun and survivability pros. Scavenger basically gives you another weapon, and you get a lot of scrap for guns.

Why melee so bad?

Parry, or shove. Or just stab 'em.

Why gun so bad?

Get professional or play soldier. Remember that First Shot Accuracy exists.

Learn the way you want to play. There are multiple playstyles and niches! Play the one that works for you.