In Starcraft, an immensely popular RTS game, there is microing and macroing (nouns). Macroing means building up economy by managing workers and buildings to achieve the greatest efficiency; microing means controlling each units to achieve the best positioning leading to higher survivability and damage output. In league of Legends, only microing exists because you only control one unit -your champion. Microing in LoL is necessary to position yourself to last hit, harass the enemy champions, and most importantly, survive. If you watch pros' livestream, you will see that they are constantly clicking -some might say a bit excessive- to move their characters around even by an inch at a time. Pros are constantly aware of their positions and their enemy's position, of course, being familiar with the range of autoattacks and skills for most characters, they can move in and out without getting a scratch. Sometimes you will see two pros moving back and forth without attacking (except for last hit) as if they are in an invisible tug of war. For pros, microing is their second nature.
Microing a champion to its fullest potential requires more than just clicking the mouse. There are several hotkeys that are very useful. For example, the "A" key allows you to move to a location while attacking everything in your path -decent for last hitting. The "S" key allows you to stop everything you are doing (moving, casting, w.e), which can help you last hit if you timed your previous hit too early. The "H" key acts as a sentry by rooting you in a position while attacking everything that comes in range until you decide to move. There are many other hotkeys which I won't go in to detail. You can find them in game via "esc" -> menu -> "key bindings", and experiment with each of them.
The two most important microing mechanisms in my opinion are smartcast and selfcast. Smartcast allows you to instantly cast a skill (except for self-buffs) at your cursor location without needing to aim and then click manually. Selfcast allows you to instantly cast a skill on yourself (heals, buffs) without needing to click on yourself. Both of them saves you a precious second, which could be the difference between life and death, kill or miss. The problem with smartcast and selfcast at the moment that discourages most players from using them (many don't even know what they are) because of the awkward default key setup. To smartcast, you have to press "shift" + skill key, which is difficult for many players because you have to basically shift your entire hand to smartcast, defeating the purpose of casting quickly. Selfcast exhibits the same problem by forcing you to press "alt" + skill key, very awkward. (if you are a pianist, you might do better). Therefore, I will teach you how to make smartcast and selfcast viable again.
Hotkey setup overview
Smartcast and selfcast custom key settings cannot be made up of 2 separate key combinations, such as "T" + "skill key" -the key binding program won't let you do that. But that's ok, its better to assign it to one key for selfcast or smartcast because its much easier than pressing 2 keys. I do not recommend assigning smartcast for skills that require some AOE aiming (e.g. ashe's volley) because unless you can imagine the spread range in your head (your cursor is at the middle of the AOE skillshot), you will miss a lot. For assigning keys, you can assign whatever you want, but keep the following in mind:
1. must be easy to reach
2. "tab" cannot be reassigned
3. make sure you do not forget the other key you unbinded to bind your new hotkey.
4. make sure you change hotkey setup for different characters. But most primary skillshots are Q (e.g. kennen's shuriken)
5. most of the time, unless you are playing a support with 2 different buff mechanisms, stick with 1 extra hotkey (smartcast or selfcast, not both), it's enough. But if you have rapid finger dexterity and want to control 8 or more hotkeys, be my guest.
Champions that should have hotkeys assigned for smartcast include:
1. champions with skillshots in any form (e.g. ezreal's "Q", Anivia's Wall, Annie's bear...)
2. optional: champions with targetable heals (e.g. taric's heal)
3. not recommended: champions with targetable skills (e.g. Yi's Alpha Strike)
Below I will show you my recommended setup.
The "T" hotkey (QWER+T)
Perhaps the best hotkey for assigning and extra smartcast or selfcast skill is the "T" hotkey. In this setup, your index finger controls both "R" and "T" -very convenient. Remember for most characters only assign one extra hotkey, be it smartcast or self-cast. In Ragnarök Online (popular mmorpg), I use battlemode (/bm) setup when PvPing and use up to 37 hotkeys. But this is not RO, and any keys more than necessary will screw up your game.
The draw back of using "T" as hotkey could be that you might accidentally press "R". But with practice and a calm nerve, not a problem.
To assign, follow the steps below:
1. in game, press "esc" -> menu -> "key bindings"
2. scroll down to find smartcast/selfcast skill X (whatever you want to setup), and assign "T" to the secondary hotkey. (or primary, w.e)
3.the "T" key's default use is for something else. Find it and unbind the default use.
Remember for most characters only assign one extra hotkey, be it smartcast or self-cast, choose the BEST SKILL. For champions with many skillshots, choose the BEST ONE.
"T" key skills smartcast champions examples (skillshot focused):
-Kennen's Q (shuriken)
-Corki's R (rocket)
-Blitzcrank's Q (grab)
-malphite's R (charge)
and many other "Q" and "R" skillshots, etc...
"T" key skills selfcast champions examples (self-buff focused):
-morgana's E (shield)
-Kayle's (E or R, your choice)
-Taric's Q and Soraka's E (heal)
and many other shields and heals.
OPTIONAL: The "Y" hotkey (QWER+TY, or QWERTY)
Use this setup if you are a support heavy champion with multiple self or smartcast skills, like Zilean (and only Zilean), or if you think you are 1337 and can control keys like mad, you can also assign another skillshot key to "Y". Again, not recommended.
To setup "Y", follow similar instruction for "T". Make sure remove "Y" default binding (camera lock).
For Zilean, I recommend the following:
-2 selfcasts, no smartcast
-"T" for selfcast "E", Time warp, to speed yourself up
-"Y" for selfcast "R", Chrono shift, revive yourself.
Good luck and have fun!