This is a collection of some of my (mostly) quality of life tips and tricks. I've sourced some from various YouTube videos and some from my own knowledge of the game. Hopefully even veterans can find something in here that they didn't know. –
Using left 'ctrl' and left click will instantly place an item into your bag/rig, or vice versa. No need to drag.
Using left 'alt' and left click will instantly equip armour/weapons. No need to drag.
While hovering an item, pressing 'del' will instantly discard the item.
Use the 'pg up' and 'pg down' keys to instantly move to the top or bottom of your stash. You are able to left click an item in your stash and then press either key and the item will move also.
Use middle mouse/scroll wheel button to examine an item instead of doing right click, examine.
While browsing the Flea Market, you can instantly return back to your stash using 'TAB'. When you want to return to the Flea Market, clicking the button will return you to the page you were on.
Repairing armour/guns using a specific trader will go towards money spent on said trader. If you are struggling to level up a trader because of the money requirements, try using this method.
To split an item stack, hold left 'ctrl', left click and drag to another slot. This will bring up a small quantity menu.
On any of the pre-raid screens you can press 'TAB' to go back to your inventory, then 'TAB' again to go back return you to the page you were on.
Save space in your stash by stacking backpacks.
Keep your gun above 93 durability to avoid malfunctions.
Easily clear a malfunction. Re-bind “inspect weapon” and “clear chamber” to the same button. Make “clear chamber” active when the button is released. Press to inspect, release to clear malfunction.
In a raid, use your scroll wheel to adjust your walk speed/sound by smaller amounts, or press 'caps' to switch from one end to the other.
In a raid, double tap 'O' to check your available extracts.
Double tapping your reload button will reload your weapon faster, but at the cost of dropping the magazine you're replacing. Only useful in a handful of situations, but may save your life.
You can prone while searching something by pressing your search key and immediately pressing your prone key after. If you did it quick enough, you'll be searching while prone.
Gear fear will cripple your progress. Invest in yourself and you will become a better player.
This game is extremely overwhelming to a new player. Use online maps, ammo charts, along with the wiki itself to aid you a little. Take advantage of offline mode.