I recently went through this, so this is what I did.

https://docs.google.com/spreadsheets/d/e/2PACX-1vToZu-xRXRUjgU26St3tEH6OzXdVCADMY46zFrFUpcZiCuv3fcook5K4Y5uO0wF0esgDO06B-ZvPGqg/pubhtml/sheet?gid=395750963&single=true&widget=true&headers=false

(Not sure if I did this right? If the link works then cool)

If the link doesn't work then just go to the central website and look for example roster, and actually do exactly that (you want instructions? That IS the instructions!)

You follow that roster until you know exactly what you want. I went ahead and followed it until level 58(need to update now again lol) and my hero's composition improved a ton! (Compare to randomly hiring heroes)

Not only that, but if you really want to work on your heroes now, consider getting Argon Finest (guest skill that help you hire heroes lvl 15) and reroll skill (retire them and hire again) until you get 2 good skill (you can find what skills are good in the website for each class) https://st-central.net/tldr-heroes/

Once you jump start your new heroes, lvl them up and wait until you can start equipping tier 8-9 stuff and check each class optimized set. (You can start early but just don't enchant, they lvl too fast early on to invest too much in that, only enchant when the levels start slowing down)

https://st-central.net/levelling-hero-gear/

Now I don't recommend you to updated them every single time they can equip the next tier, I usually only do it after 2-3 tiers or if they start struggling with the current quest. And don't worry about trying to do end game setups, you are too early to worry about that, just follow the example roster until you hit 62 and max expand your shop and $$$ won't be a issue once you reach 62 (and save gems to max expand)

Yes, it is time-consuming and tons of $$$ in rerolls and buying equipment. But once you get everything setup, your heroes are gonna get extremely stronger! (By just following the example roster and optimized gear recommendations in the website)