I find that whether or not I'm going to do well in a run is based on the first few enemies I face. If it's a bunch of woms out the door I'm gonna do alright but if it's the ergons (sp?) then I'll take quite a bit of knocks straight away that usually means I'm prob not gonna last that long.
To be fair though, I play a lot of binding of issac and crypt of the necrodancer and it's not dissimilar to how their systems work to a point. If I don't pick up enough decent items early game in BoI I'm pretty much screwed late game unless I get very lucky, so I'm used to that kind of dynamic. I found in my last game I spent much more time at the end trying to balance my cards out for the most effective use of att/def points.
I picked up a revel map card early on in my last run which is how I ended up with such a good score and actually make it to the end. The maps can get crazy spawling at times. Was able to pinpoint some good cards and go straight for the escape pod.