Before you queue have goals. CS, wards, pink wards or anything you notice you may not do as much. Don't have to many just something to actively work towards. For some idiot it's as simple as check the mini map more.
If you can develope a plan on how you achieve that goal. Again for the mini map it may be after every cs if I'm not getting traded on check the mini map.
During the game that should be your focus. Not winning. This is hard for some people as of course everyone wants to win. But if you can't cs well flashing in aggressively on your lane opponent doesn't make you better at csing. The reason you do this is to train yourself to do it habitually and without thought. Then after enough games if you focus on one skill set you eventually will instead of say hitting 75% of cs you will only miss cs you choose to give up.
A example in real life would be if you want to be a great novelist, you probably start with a goal of knowing how to spell and right sentences. Not a goal of I will right a better novel than x percent of people. This is because if you do the ladder you may right 4 books before you realise that you need a plot line for it to be interesting.
For the streamers if you main Yorick. You don't need to watch a Yorick steamer or even a top lane steamer. You just want someone who talks about the game. Then right down facts. For example at what times junglers finish they're first buff, second buff, and what times they level 2 gank, 3 gank, and six gank. Now all of a sudden instead of random wards you know you have to wards at these specific times to avoid common gank patterns.
Do you know how many enemy minions you need to perma freeze a lane? Or whether to push the second or third wave into a turret for a full lane reset? How many waves it takes to get your ideal first back item? A challenger steamer will and you can figure some stuff out watching even if he/she doesn't say it.
Watching your item replays be story critical. I mean every time you miss a cs and your weren't forced off it. Tally it up. See how much gold you lose because you traded at a inopportune time or just even miss clicked. If you have a headset and it's recorded in your game you should be saying out loud where you think they're jungler is. Then when you watch the replay you can see how far off you were. In any given game most likely a better player in your spot could have won. Figuring out why is important. Also did you see your lane opponent flash, you can see if you timed it in chat for your jungler and yourself. Did you press that advantage in the next four minutes? Did your lane opponent ever get free damage off on you? If so you miss played. Where is your mouse cursor? If your in lane vs a skill shot champ it should be super close to your champion making it easier to dodge skill shots. If your jungling is it flying between your mini map as you keep tabs on all the lanes as you clear camps.
Small steps committed to memory, habits, and reflex. Start with basics then onwards. Eventually watching replays you will see things like oh I didn't animation cancel this aa like I should of, or I missed one aa worth of damage while orb walking. That's what it takes to be good.
Best of luck
