I've found that the team order matters a great deal for DW.
Expat goes first to mark targets, debuff enemies, or to set up her next round (if she has no guns). This lets her get the most benefit from the team members that allow for card draw early on in the game, as well as giving fixer more fodder for the bitter strike. As a side note, I've found that it can be immensely useful to use Cryo ammo on Setback or Nightmist every so often- keeps them from hurting themselves or the team. Especially with a 1 point Oblivion, or if nightmist has an elder ring out.
Setback goes next. He's got a bit of everything, so he can clean up after expat, feed fixer, remove pesky ongoings, heal the team, and (if you get lucky) put out a stupefying amount of damage. I prefer to use his base power on Nightmist- it allows DW nightmist to be a lot riskier and more aggressive. Turn of events needs to be used judiciously, but pick your moment and you'll get a LOT out of it. With DW Setback, I tend to prioritize surprising fortune, since it gives more cards to those who need it. But you always need to be prepared to adjust to circumstances with Setback. Getting locked into one style or searching for that one perfect card tends to backfire.
DW nightmist requires planning. You are going to be using her spells a LOT more, so Master of Magic is a huge boon early on. It's going to be tempting to go into must form to build up a large hand, but (in general) try to resist the impulse to hide. DW nightmist is all about thinking one step ahead, so if you use that Mist Form, have a plan for getting out of it. Unlike regular Nightmist, DW doesn't really shine as the last hero standing. You can, but you'll run out of cards faster, which limits your survivability. Her enlightens work wonders on Fixer and expat, and you can get a LOT of mileage out of the book early on. Basically, once you have spells, go on the attack. DW Setback will help keep you safe from your own damage, feed you extra cards, and heal you by cashing out. In return, support your team with raw damage, mist form tanking, and support in the form of enlightened card draws or astral enemy deck scouting. Just resist the urge to hide.
DW fixer goes last. This lets him scavenge ongoings and puts him in prime position to benefit from unexpected Setback antics (like fumbling fool discarding a great tool when you have a salvage yard), gain cards from allies, and finish off enemies that were wounded by teammates. Go with the flow. Play whatever hits the hardest, and (unless you have a specific plan of attack), focus entirely on offense against the highest HP target. Eat your own things first (unless you have a tool or style you like), and occasionally whack your teammates with the crowbars to amp up your damage in the absence of other villain targets.
This specific configuration gives Dark Watch a lot more flexibility and synergy. Or at least that's what I've found. They aren't unbeatable, but they are a lot nastier than they might initially seem, and you can take on just about any enemy (though fighting in Rook City always is harder!). I tend to find that Setback is the key for the entire team- he is a marvelous support and damage dealer... And if he's doing well the team will prosper. If he doesn't... well, that's what enlightenment or the occasional crowbar is for.