Play safe and farm 'til lvl 3, after that w8 for foe to use atleast one of his skills then strike q, and e 3-4 times , dont use w unless you dont have to, mana wasting. Keep your distance and harass with e over minions if foe is close to them 'cause splash dmg. Don't use ulti only when you are low use it when foe is using strongest skills to ignore them and ignore it all so you will have good hp for attacking after ulti and you can deal tons of dmg. Lich is one of best items for kayle 'cause of q e combo, after q and e wait 2 sec for lich to restart then use w to use it again.

Use e to farm minions with low hp just do last hits so you dont push your lane but if there is lots of them clean them all at once you get fine exp and gold. Farm mage minions first they are squishy then just last hit tanky minions, 'cause better lasthits and easier farm.

Don't use ulti only for yourself or your adc use it for the one who engage, they will probably use most of their strongest skills on him and melt him down, that's why you need to ult him, it will ignore all dmg and you still will have tank for the rest of teamfight. But if they focus you as soon you see them coming on you use ulti to ignore dmg and flash out of that area, then get back and strike with everything you have.