Changing Classes - The only phase that you can equip a class is the equip phase, and doing so ends your turn.
To change the equipped class, first you need to have another class in yout class dock. Then on your equip phase remove your equipped class to the class dock and equip normally the new class.
Removing - You can only remove a card from the playfield on your equip phase. To do it, just drag the card from the playfield to the discard pile. To remove a equipped class, just drag it to the class dock.
Passing a Phase - To pass any phase, just hit the status bar or click on the phase blinking on the phase bar.
Dircarding - If you exceeded your hand limit by the end of your turn you need to discard to continue. Discarding is very simple, just drag the card from your hand to the discard pile.
Rushing - Don't play a card just because it flashes. You can pass a phase at any time by clicking on the status bar.
Pay Attention - Watch your life and your opponent's life.
Read Carefully - Read the subtype of cards. If you play a card that cancel Abilities, make sure your opponent is playing a Ability not a Spell.
Usage Cards - Usage spells and abilities, can be played before or after your attack phase. Most of these cards are "set-up" cards that must be played on your equip phase rather than in your action phase.
Drawbacks - Read the drawbacks of cards. There's no worse feeling than being at 1 life then playing an weapon that cannot block, or playing a attack ability that makes you unable to use defense cards. Make sure the opponent will seize every advantage in a a match.
Only Ends at the End - Do not assume you have won or lost the game. Comebacks happen very often and that’s why the game gets so exciting.
Life Cap - You cannot have over 20 life. So if you're playing as a Paladin, be careful not to waste your life gain cards when you have full health.
Soul Cards - Finally, when you play a Soul of Something card, notice it is a Double spell. This means you can continue your phase as the class you switched to! This also means that if you can't do anything after the switch, you need to pass your turn.