Alright, in my kayn games i know how good my champ is. During early-game, I start my bot side, because after 1st back its easy to gank or stall a little for drake. If bot isnt ULTRA gankable, (why not mid?-Enemy jungler has the same pace, why risk a kill if they can kill me or get my flash) like, if i know i will get a kill, I contest scuttle like as if im a grizzly bear, no backing off, because kayn kills scuttle INSANELY fast, and look either for a reset or a gank top. On my first reset, i usually buy pickaxe, except if i've gotten a kill beforet that,if, then wait bit to have gold for boots.
Kayn's clear, pre-form, is still fast, but boots make it even faster, so imo they're better than an extra long-sword or glowing mote. Atp, start another sequence since the camps have respawned already, do my 2 camps, starting from the one closer to bot, and when im doing the one closer to mid ill either look for a gank or clear a wave that's crashing into our mid turret, which my team's midlaner cannot get.
After, i'll continue towards top-side, clear it, if a gank top cannot be executed then look for an invade/deep ward in enemy jg, or even steal camps. Do not be afraid of getting 2manned by the enemies, because as long as you get form early, you are a beast. Surely, at this point, you should've fought somewhere, but if not, you can just gank a lane, even if you wont get a kill or flash, and camp the enemy jg at the side they've finished before their 1st back.Possibly, steal buff from them and fight for form, otherwise, if you dont' want to do that -reset
Usually, i gank top a lot, which my toplaners probably admire me for, but i just use red form,in 95 % of my games, because its op.
So, until this point it should be ~min 9 and i'd look for grubs,if they have been killed i'd go for drake or a fight. After this point of the game, ill be playing either to permagank their top for form if they're pushing a lot, or cotninue clearing.
MIDGAME: You must've gotten 1st item and 1st tier boots and form. If you hadn't, and you're behind, try to clear a lot, look for all objectives, if possible, and NEVER gank your losing lanes, EXCEPT if the laner is a hyperscaling/carry champ.
If you aren't terrible at jungle, or gotten unlucky and behind you should have item,
form and a lead. With said lead, you look to bully the enemy junglerand force drakes with teammates around/helping.
LATEGAME: having 3+ items, boots and form is really good for kayn. You shouldn't be losing 1v1's, should've gotten an objective/gold lead over the enemy team.
(This guide is made about solocarrying and all, because usually my teammates have an IQ lower than most refrigirators' setting, i MUST solo carry to win, or have a splitpushing top.)
With your objective lead, you can force more of sidelanes, clear fast and invade a lot around teammates. You should not let your enemies scale, and can towerdive solo most mid/botlaners.
For drake setup, you want to have cleared your botside atleast a minute prio drake, so you can do them after drake. Try to ward deep enemy jg if you can see most people on the map, and get the scuttle there. The fights, if you're ahead, it should either go like: Your team has 2+ on drake and others granting vision of the enemy, trying to make them back off the objective.IF a fight brakes out, focus carries, and then clean up
OR:5man drake into fight/ lane push
IF behind: Try to steal and have somebody/2 in your team splitpushing.
For baron setup, its basically the same thing, tho, if you're red side and behind you must try to steal it. If you're blue side, and dont have a champ on your team that can 5man cc, dont try to steal it, instead do another objective/push towers.
IF ahead: have teammates applying pressure towards enemies so they can't get close to baron And after you get baron, fight.

IF you need any more tips, write a comment or something, i'll answer it.
This is my first guide, i hope you like it, and i'd be happy to explain things better/ add more info