To quote the unofficial Yomi wiki[yomicg.wikia.com]:

Yomi: Fighting Card Game is a simple competitive card game that simulates a battle between two characters.

"Yomi" is Japanese for "reading," as in reading the mind of the opponent. The Yomi card game is designed to distill the high-level mind games from fighting game tournaments into a simple card game that, itself, stands up to serious tournament play.

Each deck represents one character and doubles as a regular deck of playing cards. The object of the game is to reduce the opponent's hit points to zero through winning combat rounds and performing combos.

Playing Yomi teaches you to pay attention to small clues that indicate how people think and act. Developing your yomi (reading ability) might give you an edge in other games and even in other areas of life.

• Guides for each character[www.fantasystrike.com]
  
• Getting good at Yomi (video series) by mystic juicer:
  
  • Episode 1: How To Choose A Combat Option
    
  • Episode 2: When You Shouldn't Combo
    
  • Episode 3: Picking & Learning a Character
    
  • Episode 4: How to Study a Match Up
• Yomi Forum Index: Collected Links to Important Threads![www.fantasystrike.com] by mysticjuicer
  
• Yomi wiki[yomicg.wikia.com] - lists upcoming and previous tournaments and events, meetup groups, resources to start your own tournaments, and much more

The below resource lists are pretty outdated, but still link to some handy resources:

• Links to Helpful Yomi Resources (Wiki version that can be edited by anyone)[yomicg.wikia.com] by the Yomi community
  
• Links to Helpful Yomi Resources (forum thread version)[www.fantasystrike.com] by Yomi community

• The official Yomi discussion forums[www.fantasystrike.com]
  
• Official, in-person Yomi (and Sirlin Games) meetup event: Fantasy Strike Expo[www.fantasystrike.com]

• Yomi Tutoring Dojo: find a Yomi mentor, or mentor other players[www.fantasystrike.com]
  
• Some resources from Yomi community member Zexx:

Originally posted by ZexxCrine:

[Introduce yourself]

Introduce yourself to the community or grab some help from a more experianced player in the welcome thread[www.fantasystrike.com].

[International Yomi league]

We are currently [as of 10 May 2015] taking signups for a community yomi league. The league is a round robin style tourny that takes the top players from each division and lets them duke it out in a final winner take all tournament. Last league had 40+ players. You can sign up or find out more here[www.fantasystrike.com]

[Weekly Yomi casuals lobby]

We also are starting up a casuals lobby that will be streamed every friday. Join in and hang out more info here.[www.fantasystrike.com]

Keep an eye on the [official Yomi forums, linked to above] for more community events

Do NOT hesitate to ask veterans for help. Our community was a small one and we had an extreamly welcoming community and i do hope to see you all on the forums.

There are and have been a number of Yomi tournaments, both online and offline, and in different countries.

Here's some helpful links:

• List of upcoming, currently underway, and previous Yomi tournaments[yomicg.wikia.com] (including match reports for those that have them)
  
• Tournament announcements [yomicg.wikia.com]
  
• Resources to help you run your own tournaments[yomicg.wihttp]

• Fan art[yomicg.wikia.com]
  
• Cos play[yomicg.wikia.com]

Yomi is playable on:

• The web[www.fantasystrike.com] (can be played for free, but doesn't give you access to all characters)
  
• iOS (app)

• Sirlin Games[www.sirlingames.com]

Characters unlocked on the Steam version of Yomi aren't available in the web or iOS version of Yomi, and vice versa. (As of 15 May 2015.)

Apparently inscribed and gold foil cards do transfer over, though (though I imagine you would have to have the character unlocked).