If you're playing someone like 
Lissandra, 
Kayle, 
Lulu, 
Zilean and you often find yourself not ulting yourself fast enough, try setting your "cast on self" key to "T" in your hotkey settings. I found back when i played lissandra and i wanted to initiate, it helped me a lot. Just thought id share this for some newer players who might be able to benefit from this as well. :)
Or press alt + X key
but i have t reserved for putting my most spammable emote, laugh, or taunt on
The number of times I've thrown games because the stupid Liss ult didn't cast on me is TOO DAMN HIGH, thanks for this
I use my Alt + key. It's better because it's always there for all abilities and all champions. With your idea, you have to swap everytime. What if you wana cast a speed up on yourself on ZIlean as well? Eventually you have to use self cast ALT + key. I find this extremely useful when I play Janna and Orianna with the E shield. ALT + E.
But if it works for you, then it's a good idea and it's good to share because it might help other players as well.
T is for Trinket. The fact that Riot didn't automatically set Trinket to T tilts me.
not a bad tip although im so used to having my thumb hover over alt after maining liss for a couple years and now kayle for a year that it would be hard to change ><
Remember when i played URF with Karma and i put the E on self cast. OH apm went skyhigh
