The dev pretty much gave you the keys to the kingdom, but its definitely worth emphasizing that, if you can at all costs, avoid letting any enemy get to their preferred zone to attack you. In my experience, generally if you wanna have certain enemy types to focus on in particular, I'd suggest: Archers > Blue Guys > Dogs/Wolf enemies (move two spaces) > red brute guys with clubs.
Can be a bit interchangeable between the archers and the blue mage guys that want to get to the middle of the screen, but archers will almost always be something you want to end very quickly since they get to attack out the gate, and unless you have a way to reliably pull them into the center, or the red zones (Ninjas Grappling Chain skill), you'll pretty much want to focus on taking them out since they have low HP pools anyways, and the Archer can one shot them fairly often.
The blue mages themselves aren't too dangerous either, and are the tankiest of the generic enemies, but they do have ONE ability which can put you in some serious trouble, and that's the ability they have to buff other enemies so that they can attack/harass your characters no MATTER the zone they are in. If you can, keep them out of the middle zone at all costs, or kill them. Not a big deal to let one or two in for a little while, but if they just get to sit there for free for too long you'll run into issues.
The two units that want to be in the red zone, I find, are generally the easiest to handle, and also happen to be some of the least threatening. The dogs get a special mention cause, and while I haven't necessarily confirmed it, they only do stamina attacks, and seem to do a pretty hefty amount of stamina per attack. That and the fact they can get to the red zone in half the time the brute guys do, and they automatically become a bigger focus when one of the other two above this aren't up.
The brute guys just kind of get filtered out on their own in time as they reach the red zone in my gameplay, and are usually, if any, the ones that I keep alive to hopefully push a girl over 0 SR to refill it and get the buff, while sitting at low hp so you can immediately delete said enemy once they've done so.
Following with this advice, find out, and always try to keep bosses out of their preferred range, or you WILL suffer for it. Could give a small guide on what each range bosses prefer if people want, but realistically it'll become pretty easy to figure out once you see them either try to stick in the green zone, or try to move into blue or further. Also, most bosses generally have two zones in which they can do some sort of ability to harm you I've found, though, this doesn't seem to be universally true.
Really, the games just all about minimizing the possible damage you can take, therefore maximizing how much you keep enemies out of their preferred zone. Don't spam abilities needlessly, but also don't be afraid to use them and just sit at 100 Stam/100 SR, especialyl the former as you're effectively wasting free damage and resources by just sitting at 100 while doing basic attacks. Especially when you have abilities that can do damage regardless of zone, and deal your characters full damage, its almost always worth using these when a decent opportunity arises, and you have very high/max stamina.
Really, this is just some general stuff rogue-lites tend to emphasize overall, and you're not always going to be set up to win, but you can do a lot to mitigate chance and circumstance in your favor by just understanding how to combo skills, movement, and enemies preferred zones as well as their abilities. Sometimes its just worth it to hit one of the mini bosses when you are having a bad run, and get a few bright coins to spend for items or skills, sometimes you'll have the tools to basically trivialize the game. There's only a few skills I feel are generally not worth having either due to their cost or effect, but with the right tactics and maybe some small bit of favorable RNG, you should be able to come out on top in most cases so long as you're being smart about it.
Also, always hit up the shopkeeper in a run if you can, and plan to go all the way to the end. Some items can basically just delete bosses for you, or get you out of a really bad spot given how much damage they do regardless of zone. Also, getting a choice at a potential skill opposed to a single random one from a chest is always great as well.