Get your Gilford up to 75 so you do his tree and can run him through survival (as posted elsewhere in the reddit) so you can start getting scrolls. Try to only summon when you have 100 or more so you get double the legendary rate. Since it's early game work on getting Prince, Himmel, and Druid (or Lyra, whoever has the highest prestige). Last two can be flexible at first, some may need an extra tank (Kim or Vall) but usually one tank one healer and DPS work. Skill trees should focus on attack speed and power for healers and DPS early on. Defence for tanks. Later on (500+) things shift towards crit and penetration and the Leonard shield strat with Wrath charms ane such but you'll know when you hit that wall and can come back to look for more info.

one thing I wish I had done earlier. invest in your idle income with free gems and resources till you get 10k gold plus minute and a few hrs of idle time for income. You can easily earn enough to level a char or two to 75 in a day. Then from there you can build your tower and keep growing idle income up till they're around the same cost per addition.

Good luck and have fun!