First thing to would be to select, train and ascend a rainbow 3 star team for map quests and rare events. Three stars can get you a long way. Don’t train 5 star heroes yet, I can see you’ve pulled some which is great, but start with the threes for now
Select a team. I’d say Belith . Balthazar . Azar . Bane and Gunnar. Good mix of abilities, and a healer.
Give these heroes on colour feeders (all the yellows go to Bane, all the reds to Azar etc). Train them all to first ascension, ascend them (with relatively rare materials you will find), and gradually get them all to 3/50, fully trained. Use this team to do everything for a while, then train a second team of threes. Maybe Hawkmoon Karil Berden Tyrum Kailani
After you have at least three such full teams fully trained, start your fours, like BT and Grimm who are excellent choices. To ascend these heroes to final ascension you will need materials you can’t get from normal missions but you will learn all that as you go
Five star heroes need to wait a while
Check back in after a few weeks to see how you’re going and have questions. This game is a marathon, not a sprint
Fives will wait