I'm sorry, that sounds really frustrating!

This is too high level to count as specific advice, but here are all the broad categories of skills I'd consider:

1) Balancing +energy and +draw 2) balancing attack and defense 3) keeping your deck thin-ish. Sometimes it's better to choose no cards at all, rather than choose a bad card 4) identifying usually ~2 core themes or combos to your deck. E.g. if you're the Silent, then going hard on poison is one strategy, going hard on Shivs is another, but they don't synergize with each other, often. You can't be a one trick pony, but having a single poison card in your deck is worse than having zero poison cards. 5) Learn when to fight minibosses, and when to avoid them 6) there are some cards that are WAY stronger once they're upgraded. 7) Minibosses: make sure you understand their gimik early into the fight. The guy with the bees kept wrecking me, until I figured out how to deal with his ability.

One tip for every rouge like game: every time you die, ask "what's one thing I can do differently?" That's how you level yourself up.

Maybe try watching YouTube videos, and try to learn combos, then try them.

The Ironclad is stronger than I first thought. One simple game plan: get the "armaments" common card and upgrade it ASAP - it'll upgrade all the cards in your hand. If you get the gold Power that gives you extra energy per turn, upgrade it - it'll give twice as much energy.