Level 1: Play safe and focus on farming with your Q. Avoid taking unnecessary poke just to get CS. Your main goal is to preserve HP and reach levels 2 and 3 safely.

Levels 2-3: This is where you can start looking for opportunities to trade or even get an early kill. Once you have your mobility and daggers available, you can jump onto the enemy if you're facing a squishy mage or assassin. A great opportunity is when they waste an important ability or their main CC, since they will have a much harder time stopping your engage.

Don't force a kill if there isn't a good opening. Staying healthy, getting XP and waiting for the enemy to make a mistake is much better than taking a bad trade and losing control of the lane.

If you leave lane even: Focus on playing the sidelane, farming waves and getting as much gold and XP as possible. Your main objective is to reach your second-item powerspike without falling behind. Don't force unnecessary fights; farm efficiently and rotate when a good opportunity appears.

If you leave lane fed: Your game plan changes completely. Use your lead to constantly pressure the map. Rotate to objectives, force favorable skirmishes with your team and look for kills whenever enemies are out of position. Katarina is extremely strong when ahead, so don't waste your advantage by staying in a sidelane farming all game.

Look for fights around Dragon, Herald/Baron and jungle rotations, especially when your teammates have reliable engage or CC. One good fight can give you multiple resets and completely snowball the game.

In the late game, your main targets should usually be the ADC or Support. Once you have your core items, Katarina has enough damage to one-shot most squishy champions and immediately start chaining resets.

Be patient before going in. Always identify the enemy abilities that can interrupt your ultimate or instantly CC you, and wait for them to be used before committing. Going in too early can get you killed before you deal any damage.

Look for a safe angle or flank, wait for the right moment, then jump onto the enemy backline and use your combo. Your goal is to burst a priority target, get your first reset and take over the fight from there.

Remember: you don't need to engage first. Let the fight start, wait for important cooldowns, then go in and deal as much damage as possible.