start here: Master List of E&P Links & Player Guides
then here: New Player - Need Hero Group Makeup/Leveling Advice - #14 by fight_happy
What helps a lot : find an alliance with players looking to learn like yourself Teaching Alliances
What I learned early to save myself headaches: don’t chase five stars, focus on growing a solid army of 3s then 4s. And don’t forget that levelling troops make a major impact on gameplay (level your troops before even getting to five star heroes).
Have fun on your long journey with this game.