Which Colours to get next, which heroes to develop [Beginner]

Great advice from @NPNKY. There’s a wealth of general information on these forums that I hope you’ve been reading.

The index to core guides is here: Master List of E&P Links & Player Guides

Guides of particular interest to new players are listed here: Complete Starter Pack for New Players

You ask about using gems. The lowest value use of gems is rushing builds. This is a slow-paced game; just accept that. Atlantis summons are good value, particularly because you get a rare or epic ascension item every ten pulls. There are some excellent heroes there you can’t pull elsewhere. Of the event summons, Guardians of Teltoc and Knights of Avalon have uniformly very good-to-great heroes. Those roll around monthly, as does Atlantis (which will be coming up on Thursday).

Don’t ever use gems in the Epic Hero Summons; odds are much better in Elemental.

Enjoy! Ask questions as they come up if you can’t find answers somewhere already posted.