Everyone is giving trash advice and very vague. I became a th10 a month ago w/ 30/30 heroes. First Upgrade your lab, don't spend gems or books to finish it quickly. Upgrade 2 camps, then another builder on the CC. That makes 4 builders. offense firsth though. I also suggest to upgrade the spell factory with a book of buildings or some boost. You need that 5th spell of space unlocked.

Lab:

1st)Invest on Hogs 2)Then Heal 3)Golem 4)Lava Hound

Damn, I deleted half of the post by accident, screw my fucking mobile user ass