I might be a bit extreme but..
I've been th9 for 6 weeks tomorrow, and i currently have 77 skills left to go towards legos. My goal was to have full legos before my defenses were all maxed (not even halfway there lol).
What i do: i stockpile resources and try to always have 2 days in between a free builder (i have 5). So in those 2 days i try to farm up about 8mill resources combined. And Then i level up about 3-5 walls before upgrading a defense or a Hero (lvl 10 AQ tomorrow! #cheer!)
Good luck with your grind mate!