I use
Sensitivity: 4 / 800 mouse dpi
Reticle: Circle
Thickness: 1
Center Gap: 11
Color: Neon green
You aren’t going to like hearing this but wrist aiming is almost impossible to be consistently good with. You will have moments where you do good, but you’ll never consistently be hitting shots when averaged over the long term. You just don’t have as much control using small wrist muscles vs your wrist + arm. I was the same way as you but one day I just took the plunge, dropped my sens to a painfully low level, and just got my body used to having to move my whole arm. It will take a while to adjust, maybe a month or more depending on how much you play, and you will be horribly bad and feel like its impossible, but eventually your aim will be much better than with wrist. I remember when I tried returning to my old sens and I couldn’t believe I ever thought I could control such a slippery thing. Make sure you get the proper mouse for this; I recommend small + light (I use Finalmouse Ultralight2 but I also have below average sized hands).
For this game in particular, you can’t drop your aim to CS Go levels because there’s always stuff coming at you from different angles (think Tracer or Genji dashing through you) and you have to turn quickly. I’ve tried lower than what I listed before, and it makes it impossible to play characters like Tracer, so I think what I have is about as low as you’d want to go in this game unless you’re going to be a hardcore Widow one trick or something and don’t mind getting shredded if a Tracer or Genji jump on you.
For aim technique in particular, you definitely want to flick, but how and when you flick are important. For me, most of the time, I flick, shoot, and then pull the reticle off of the person slightly and flick again. If you try to track a moving target, a lot of the time they will move the opposite direction just as you shoot, and you can’t react in time because you have to overcome the inertia in your hand, whereas if you flick, your hand is always moving in only one direction and only thing you have to do is click at the right time.
I say I “mostly” do it this way because people are mostly always moving. If you do this technique vs a completely stationary target, like a Mercy rez, you will find you end up missing a lot of shots that would have been easy had you just held it on them because you’re never going to flick perfectly each time. The same thing occurs when players move in a straight line. It will always be easier to track and hold on a player instead of flicking, as long as the player lets you do so (stands still or moves predictably). So you have to be mindful and not go into robot mode with flicking and identify when these periods of times are. An easy one to identify is whenever you get a player low, they will almost always stop strafe spamming and bee line straight to the nearest piece of cover. Pharah players like to stop floating and just drop straight down as soon as you hit them once or twice. Whenever you see you’ve initiated this, stop robotically flicking and go into tracking mode to get an easy finish.
This next part sort of follows from the previous, but try not to just spray out your bullets as fast as possible. A lot of times this is fine and the best course of action if you’re just poking and feeling out what’s going on, but in a straight duel, its better to wait for moments where you know exactly how your opponent is going to move rather than just guessing. For example, when a player jumps in the air, its an easy hit because they have limited mobility and are on a fixed trajectory. You know as soon as you see it that you can take a small extra bit of time to line up the shot rather than just robotically flicking. Its the same with AD spam; if you see someone start doing it to you, STOP firing as fast as possible, hold your aim steady, get a read on their rhythm, and just fire each time they walk into your crosshair. Since you play Widow, this is akin to being scoped up and when you see the enemy Widow jump out from cover, you don’t fire immediately; you let them land and you then you carefully line up the headshot because you know you have the time to do so because their shot isn’t charged yet.
These tips are really just finishing touches though; 95% of it is just practice and muscle memory grinding. To make it go faster, make sure you always play McCree and make sure you aren’t just blindly playing; go in with a specific goal, like hitting all headshots, or just trying to have the highest accuracy possible, rather than just winning the game. This will force you to slow down and make sure you’re hitting the shot. Over time you will build speed because all of the stuff you’re having to slow down and think about will just get absorbed into your muscle memory and you’ll start doing it without thinking (but remember not to completely turn your brain off as mentioned previously; its a balancing act).
I want to mention too that currently the game has a very bad cheating problem so try not to compare yourself to others too much if they beat you in a duel. Just work on improving your own stats, not beating the enemy, and hopefully when OW2 comes around they will bring this game out of life support, start cracking down, and you will be able to see all your hard work pay off.