Play to your outs when the normal plan fails
An out is a draw or event that could help you win from a bad spot. Choose a play that leaves your outs usable.
Look for a real chance
An out might be a certain draw, a made card, a lucky effect, or an enemy response. It matters only if it gives you a real path to win.
A safe-looking play may only delay a loss. If all safe plans lose, a risky plan with a small chance to win may be best.
Being behind does not always mean you need luck. Check for normal ways to defend first.
Get ready for the good draw
Suppose one spell left in your deck can save you next turn. It needs enough Mana and a legal target. Your play now should leave those things in place.
Drawing the spell will not help if you have already used what it needs.
Compare several outs. A plan that wins after either of two draws may be better than one that needs a single card. Check whether the enemy can still stop you afterward.
Match the risk to the game
When far ahead, avoid risks that can throw away your lead. When far behind, a risky play may help because the normal result already loses.
Random effects are not always good or bad. Look at the possible results.
Judge before you see the result
A low-chance play can be your best option and still fail. A bad play can get lucky. Review the choices and odds you had at the time. Ask whether you found and protected your real outs.