These tips can make your life easier as a beginnner.

• Never spend Hero points to anything else than spaces for your rooster, you'll need a lot.
  
• Never spend Iso-8 to anything else than levelling up characters.
  
• Always participate in events, you can win some Hero points and cards there.
  
• In events use the buffed heroes (the ones with a crystal in their picture), they have better HP, damage and ability damage, so they can beat up lot of higher level enemies while need healing less often.
  
• In pseudo-PVP events choose your enemies wisely (press skip, to get a new one), you get more points if they have much more than you.
  
• Level up the usefull skill common heroes first, like Iron Man (model 35) for damage, Black Widow (modern) for mana steal and stun and Storm (modern) for block removal. You can get their abilites quickly from drops. Feel free to find your own favourites though.

Knowing this restrictions can make you less frustrated:

• Don't try to play this as a usual Puzzle Quest. It's a mobile based F2P game, made to play just a few rounds every 2-8 hour. Or pay for healing your characters after you ran out of Health Packs. (The more your hero is advanced in level/HP the more time it need to heal.)
  
• Don't try to enjoy pseudo-PVP too much. Get in, get the points you need fast (100 at first, for the cards), get out. After a while you get attacked and loose points anyway. The more points you have the less you can get, and the more you can loose.
  
• Don't sell heroes with levelled up skills, if you recruit them again you'll have to start over getting the cards.
  
• Yes you need cards to level up skills, and need levelled up skills to level up the character itself. It means you won't have high level rare characters for a long time. You better decide now if that's still worth it, or you should change to Puzzle Quest 2.

UPDATE
Looks like you don't get attacked and loose points in PVP any more. But you still can buy shield to prevent it. I'm quite confused.