F2P Beginner Guide

Hi guys, I just started this game a week or two ago, and I have come to realize that as a F2P player, I won't be able to compete at the same level as players that spend money. I would still like to play the game however, but am confused on how to proceed. I am not sure what heroes I should focus on, what to spend my gems on etc...Is there like a beginner's guide for F2P players? Thanks!