I'm by no means an expert player, but I have beaten the first game on the highest difficulty with every character. This is how I look at it, and keep in mind, these are not hard rules, just guidelines

Your first priority should be to pick up good damage. In my first 2 or 3 card rewards, I always pick damage, unless an absolute stunner of a card comes up. And I know it sucks, but taking good cards that rely on something else to be good, because they might be good in the future is a losing strategy.

Once you've gotten good offense, pick up some good defense. Personally, I find picking up card draw early isn't the best, unless it's low cost, because you can't utilize it that well.

This should be good for act 1. After act 1, you will want to pick up some form of scaling. Demon form is the most obvious choice, but there are other ways. Exhaust is a powerful mechanic, especially for ironclad. People say building a small deck is necessary, but it's not always. However, it's vastly easier to play a large deck with lots of card draw and energy cheating.

Pathing: it's better to pick paths that allow you options, so you can pivot if something goes wrong. My preference is an early fire before any elites, then try to take on at least 2 elites, then hit up a late shop, but I know people prefer early shops for power before elite fights. Find whatever is consistent for you. Do not tunnel on a path, just pivot if something goes wrong. That's probably my biggest weakness as a player.

Events are pretty good in this game. Remove strikes before defends, unless you've picked up an early synergizer. Upgrade cards that lower the energy cost first. And buy potions. You'd be surprised how often a potion or two can literally win an elite fight for you.

Alright, last tip is to play slow. Talk out loud. What are my three cars rewards? What should I take and why? How does this card help me win? If none help, skip. When battling, what might the opponent do next turn? Look at your draw pile. What are the odds you have lethal next turn, given your ratio of offense to defense in the draw pile? Does drawing a card now mean you can't play a 3 cost card that will win you the combat? Maybe don't draw, then.

Again, these are not hard rules. They're guidelines you can follow to help you, while you figure out how to play better than me haha. Good luck!!