Here I am going to share some of my tips based on my own personal experience along with some helpful builds I have found thanks to other players.
The Dark Zone: As we all already know, the DZ is a lawless area within the game, if you've ever played games like Day Z or H1Z1 then you know what it's like to balance your trust & your trigger finger, the whole to kill or not to kill mentality. I can't count the many times I've manaed to get a massive amount of good loot only to end up being ambushed at extraction by a bunch of rogues and have it all stolen.
My first tip is to never, never go alone if you plan on extracting anything, do not trust random players cause they can just be waiting for the right moment to attack & always remember that there is a high chance that these opponents may be way better equipped than yu and your team.
avoid any confrlict if you must but if it's unavoidable then do what you must to hold on to your precious loot.
Another thing you may want to try is to focus on leveling up instead of extracting loot, if you focus on just killing enemies and hunting down rogues then you may actually level up faster, just be sure to have equipment which may give you an XP increase per kill, even that 4% chance is helpful in the DZ cause the grind to 50 is a long one.
Choosing your build: This is one of the most important things that most players may just overlook, the purpose of buying or earning that new gear is to help you build your character. One of the main stats you do not want to overlook are HP & Electronics, DPS does not matter unless it's something where every shot is connecting like an assault rifle or SMG, those do not matter for sniper rifles and Shotguns which can either be a slow double barrel or a bolt action marksman rifle.
I for example have a tank build which is focused on close to long range, it's a bit of a hybrid build that needs some serious work once I get the right equipment for it. A good build should be able to make it through a daily challenge on challenging difficulty without any struggles at the very beginning of the missions.
Here are some listed builds by websites like IGN and others.
IGN Class builds
Gamespot Builds
Rock Paper Shotgun Solo Builds
The Division Forums Character build guide
There so many good builds, so many of your own hybrid builds that can be created as well, it just takes some time experimenting with your gear and see what works for you.
Teamwork: The best way to make it through daily's and survive the DZ is making builds that help out the team. Obviously we know a tank is a damage sponge, they should be able to draw all attention to themselves, away from other teammates, the healer is supposed to make sure that the team stays alive nd especially the tank cause if the tank goes down, all attention goes back to the guys who cannot withstand the damage, making it more difficult for the team to stay alive. The tank and healers are the most important jobs on any squad.
Then you can have the tech player which can focus on bringing in a gun Turret and laying down sme good DPS or suppression fire, the other should be a long and close range damage dealer, this will help the team lay down some serious damage, especially with the tank drawing all the attention.
Remember, this game is all about teamwork, without the teamwork, you're going nowhere in the DZ & most definitely not surviving a daily. So make sure you discuss with your squad wht roles you want to take up before heading into battle.