Just posted this over on the MC forums - duplicating here:
So, I've been noticing that my CS has been somewhat awful lately and decided to spend some time working on my mechanics. To that end, I searched the net and came across a few things, but 1 in particular stuck out - a guide on reddit called "learn to cs like a challenger." (linked). Worth a read imo. I'm going to highlight a few things from that post and talk about what I'm doing to improve via 5 minute drills.
1st - CS in league is really, really important. You get more money, you get better items, you get higher kill potential, etc. Here's a really good example:
"If we assume the average minion is worth roughly 20 gold, the maximum I could earn from minions by 30:00 is 7,100 gold. Instead, I earned 3,000 gold (with 150 CS at 30 min). This is a difference of 4,100 gold, which equates to 14 full value kills. This means that a 5/0/0 Akali with 100 CS by 20 minutes has earned the same amount of gold as a 0/0/0 Graves with 175 CS, and that's only if we ignore the diminishing returns for repeated kills on the same champion."
So, last hitting = good to be good at, eh. The article goes on to suggest several drills. I'm just going to walk you through 1 drill setup, the max CS possible at 5 minutes, and tell you how I did in my first few tests.
The 1st 5 Minute Drill
So, the setup: use whatever champ you want, runes/masteries you'd normally use, same thing with items. Create a custom game, don't add any AIs, start, and go to whatever lane you want to practice. Top/Bottom lane can get a max of 38 cs at 5 minutes. Mid lane can get a max of 44 cs. I suggest using excel to keep track, but use w/e you want. I also suggest using the same champ during the drills so you are comparing apples to apples.
Round 1 - just go to lane and farm however you like - move around, w/e. Track your results and also make note of why you missed some. A tip though - look at your AD dmg output so you know how much dmg you do per hit. Left click on one of the enemy minions so you can see its health bar stats and observe how quickly it drops, etc.
My stats (all games played as trist):
Goal 38 CS
25 CS, % of Goal =65.79%
Ugh...
Round 2 - intentionally choose to stand still by pressing S (S keeps you standing still and keeps you from auto attacking). Track your stats and note why you missed some.
Goal 38 CS
34 CS, % of Goal = 89.47%
notes - choose to stand still a bunch more
Rounds 3/4 - repeat
Goal 38 CS
33 CS, % of Goal = 86.84%
36 CS, % of Goal = 94.74%
Anyway, the link I provided covers various other drills. I personally think its worth the time to develop your mechanical skills as that difference in gold income can mean a heck of a lot in game.