Champ says:"I'll use my ability when im good and ready to"

As the title suggests, when i am playing most champs, there is a seeming delay between keystrokes and my abilities being registered resulting in my needing to "urf-mode" my keys, that is rapidfire in quick succession in order to get my abilities off.

I have a "consistant 68ms?" and im marginally sure my internet connection is stable, though i could check if required... and i have a mechanical keyboard, (have gone through a few different ones in my time of playing league) But i am at my wits end trying to figure out why my champion does certain things. It could be just that I am using the wrong keys...

But if that's the case, please riot I would love to see a practical tutorial on advanced mechanics built in to this game... Like how to stop auto-attacking a minion when your chasing (I use rmb i think... that could be wrong?) And to the community at large here, please help!