As kayle, Play safe in the early game. You need time to come online and if you fall behind, you will struggle to lane and you will delay your first major power spike. 

Focus on power farming and minimizing trading until you’re level 6. Once you unlock your Ultimate R, you can start to be more aggressive.

Once you’re level 6, you can look to play more aggressive as you can use your Ultimate R as a trading tool and something to fall back on. As kayle, Play safely in the game early. You need time to come online and if you fall behind, you'll have trouble in the line and you'll delay your first major power peak. Focus on electric farming and minimize trading up to your level 6. Once you unlock your Ultimate R, you can start to be more aggressive. Once you're level 6, you can look at playing more aggressive than you can use your Ultimate R as a trading tool and something to come back on.