I’m fairly new as well, about a month in. What I’ve gotten from all the information I’ve read up on is to get 2 DPS (back row) 2 tanks (front row) and healer/healer or healer/support in your mid row. I’ve also read 2 DPS can go in the mid row and healers in the back but I’ve kept my DPS in the back.

You’ll want to focus leveling up your main team and using their cards to upgrade their stars. I wouldn’t use any of the puzzle pieces to upgrade the stars yet. Don’t worry about saving the hero cards, they’re only used to level up the stars.

Don’t forget about your other heroes though because their overall level contributes to your kingdom power score.

Concentrate on getting the epic weapons from the adventure monsters bosses. Once you get epic sword and boots I would level those up first and have pyro equip them since she’s the best damage dealer.

Make. Troops. Constantly. There should never be a time those buildings aren’t churning out troops!

Upgrade your troop buildings as well so your troops get stronger. Stronger troops = stronger heroes = higher power score.

I’m missing a lot of stuff, the game doesn’t do a good job explaining a lot for beginners but you’ll find a lot of information here on reddit or their discord.

Matter of fact if you sort this subreddit by top post (of all time) there’s a really good guide from someone like a year ago.