GENERAL DARK ZONE TIPS
For the most part, run first-aid with overheal and pulse with damage.
Avoid DZ02 like the plague, especially extractions. If you extract here you're asking for it. DZ02 is by far and away the hub of the Dark Zone at the moment and where most hostile exchanges are found in my experience. This isn't helped by the camp-zone by the DZ02 entrance that is currently favoured by manhunts (though if you're ballsy a shock turret + pulse and work wonders).
If, for whatever reason, you need to extract from DZ02 (don't) then pop the flare closest to the ledge with the fans, behind the barrier and in cover of the boxes. Hide up there, don't show face and keep watching the helipad and occasionally behind you. Pulse at 3 seconds and look for white markers. If you see one, leave. If not, pop an overshield and go down and extract.
Wear black/white/grey. It's just harder to see, probably doesn't affect too much but it's in the "can't hurt" category. Anything to help make me more invisible is of benefit.
RUNNING AWAY
If you're playing solo and not planning on taking risks: if a bullet hits you that you know isn't an enemies, run that second. Don't try and engage, don't consider anything, just run. The sooner you get to running the less chance they have. They need to stop to properly aim and once you're around a corner they have to start looking where you went. This is all slow, you are not.
Use enemies. Turn a corner into a bunch of enemies (the wide alleyways and contamination zones are often good for this as well as the DZ03 extraction zone as a whole). Pop overshield and get ready to use a medkit, and then plough right into the middle of them. Still, don't stop. Those few seconds of enemies realising your there allow you to get through alive but it becomes a harder job for those chasing. At the very least it makes it harder to assess where you could have run to as there's now bullets and fire hitting them, at best they get caught up having to clear a route.
Running away is easy in this game. First Aid can be popped while running so always use this when escaping whenever it's up. When using a medkit make sure - if possible - you've got an object between you and the bullets, hit it and click sprint again.
Evading people is both effective, very accessible and extremely cool. The first rule is distance. Take the shortest route and always be mindful of where a block will lead to nothing. A dead-end will get you killed. Use med-packs and first aid to survive you and never turn around to engage. Even if someone runs out of a building in front of you, keep going. They have to pause to do things, your only concern should be running.
The second rule of evasion is line of sight. The beautiful thing about this game is that players - bar rogues - won't appear on your minimap. When you're running, put obstacles between you and them. Jump over a barrier, put cars and trucks behind you.
When line of sight is broken, take turns. Cut through an alleyway, wrap through a house. Never go upstairs if you don't know there's a definite way down.
Do the above until you're as sure as you can be that they can't see you, even if they're following you it's the line of sight that's important. Remember they have to knowyou've stopped before they can stop, pulse and look around.
When you are sure, duck into a corner or behind something that's hidden from the obvious route you would have continued to take. Use the camera to peek around the edge and wait.
There is little else as satisfying in this game than seeing the four people that were chasing you continue to run down the street past where you're hiding. This happens a lot when you get used to the above and it's one of my real highlights of the game. Once you've seen them run past, move back the way you came (away from them).
FARMING/PvE IN THE DARK ZONE
It's entirely possible to PvE in the DZ as a solo player. This needs to be clarified.
Subways are often your friend. They're marked on the map and easy to find, their layout means kiting enemies is very effective and makes handling mobs much easier. They also usually have a name-boss and a key-chest as well. They're also out of the way and people are very visible when pulsing.
Always pulse when you have it up. When you're fighting enemies, go behind cover, pulse and take a few seconds to look around for other players. At the same time look out for other signs of players such as rogue symbols, icons of healing stations and sounds of fighting. Always be aware of what might be coming and monitor it.
If you spot more than one person, or suspect a group, is coming then run. Any other decision is a gamble. Make sure you land a few decent shots on the named boss and then revisit it later. It sucks leaving a potential drop, but that dorp is null if it's going to be stolen anyway.
If you have just dropped a name boss and see a HE drop, and then see people in the close vicinity (visible to you) then make a note of where you are and come back for it.
I would recommend starting at DZ03 for farming, even if it's a little above your current gear. This is where I started to get HE drops from named bosses (never had one from a DZ01/02 boss) and it's where the population starts to thin a little and starts to get a bit more spread out.
The DZ03 extraction zone features a key-chest and a name-boss but does take time. It's both the most annoying and most ideal spot though. Annoying as the enemies can be hard to handle when solo, but ideal because when they're cleared you have a name-boss drop and a clear extraction zone to shoot off from.
Before you enter a landmark (meaning at all) do a pulse and see who else is up there. If there are people, move on. Of course if there's one person then feel free to go in but be aware of the risks, keep an eye on where they are at all times and as soon as you're done move away. Again, if a HE is dropped then leave it there and come back when it's empty.
If a HE drops, always fill your backpack. For this reason it's useful to try and leave streets littered with the greens/blues that have dropped as it means you don't need to spend much time to do so. This is because when you are killed, your inventory is split between public and private drops. It's random, but a couple of times I've saved myself the trouble of having a gold beam visible while I try and run bank, being that it's in my private drops.
To bag or not to bag. This is a tough one and there are valid reasons for both. With a yellow bag you're more likely to be targeted by people who want to go rogue, but less by people with stuff that you come across as you don't appear as threatening when you have something to lose yourself. Without a bag would-be rogues will leave you alone if you make it hard for them (you should be running from people remember) but if you stumble across a couple of guys with loot they may think it safer to knock you out.
I typically run without a bag. Rogues being rogues for rogues sake won't get me as I'm either running from them, or running having seen them. People with gear get a little shaky but if you're very clearly not interested (don't stop, don't nosy around, just keep going) then it's not in their interest to try. If someone does, it's almost always a warning and if you keep running they won't chase. They have something to lose, you don't.
Never leave with a full stash. This might seem like a waste but I only fill it to 28 before I'm making my way back out. Why? There's a chance, somehow, an item might drop on your way there and if it's one you need it is gutting to have to leave it in the dust. It's happened to me before (had to kill a few enemies blocking my exit and one dropped gloves which were better than my current ones) and I can't imagine how it would feel were it a high-end. Leave a slot or two in case this happens and you need to go back.
EXTRACTING / GETTING YOUR STUFF OUT
Again, don't extract from DZ02.
If you're being chased - or think you might still have people after you - then pop a flare and run to the next extraction. They will be forced to look around for you for a bit and then have to guess where you went next - and that is rarely worth the effort.
90% of the time I'm extracting HE gear I'm doing it from DZ01 East. I find this a very manageable Extraction Zone both because the enemies are very weak, and also because you're in a courtyard. Keep that pulse going out and it's easy to see where people are hiding. Pop the extraction to the steps to the left of the containers (looking from the gas station) and behind the boxes. This provides cover from the central area, the steps by them and the steps on the other side, with containers in the alley.
If you see people, move on. It's annoying if it's only 10s away but it's not worth the risk.
When extracting, pop the flare and hide on the opposite end of the area (so for DZ01 east I hide behind the generator by the tent on the bushes side). People assume those hiding are close to the helipad from my experience and this will allow you more time to spot people inbetween pulses.
If it's clear from people but there are a few enemies left around, don't engage them, beeline to the rope and pop overshield + survival link. It's very rare to take enough damage to go down before you've got your stuff hooked on. This obviously is limited by your gear but you would be surprised how much you can take from enemies with those combined. The only caveat is melee enemies, as they will knock you away from the rope. If you spot these and they're yellow, you might be best to clear the zone.
With regard to clearing enemies on an extraction zone, treat it as I have landmarks above. Hide behind cover to pulse, check, continue, repeat. It's not an extraction zone until it's clear and the rope has dropped. Until then you're just farming. Any other mindset and you're going to get frustrated if you can't clear it in time. I usually only pop the flare once the place is cleared of enemies as a result.