I have played over hundreds games in the past year since i started LoL,and have only been able to improve when people tell me where to improve on and how to do it. I am in silver and not going anywhere,so i need to improve my mechanics yet again if i want to move on. So you Gold+ players,what sort of mechanics do you naturally employ and/or see in your matches?
Know if your champion has an AA reset, and use it effectively.
If chasing an enemy through a bush, ward the bush as soon as you're in range. If you don't have a ward, hit A to attack-move into the bush. This ensures that you will move directly towards and/or AA the target as soon as you have vision on them again, even if they juked you while you couldn't see them.
Carefully watch which enemy minion is being targeted by your siege minion. That target will take larger chunks of damage and will die faster. Try to notice which target it switches to each time its current target dies.
If a wave of minions is incoming to your tower, immediately assess which ones will not be killable in 1 AA between tower shots. For example, a melee minion at 75% health or a caster minion at 50% health. Plan out which minions need to be "prepped" with some damage and in what order, or which minions you should use abilities to kill. Towers will target siege minions before smaller guys but they will not immediately switch targets as soon as a siege minion comes in range.
If someone on your team has long duration CC (Warwick, Morgana, Rammus, etc.), do not immediately use your CC on the target that they catch. If you are Pantheon, for example, don't use your W to jump on an enemy who just got caught out by a teammate.
Ping OMW when heading to a lane to gank it, then ping 2 or 3 times right when your want your teammate to engage. If he wants to wait longer to engage, he'll disregard your pings. But if you don't ping at all, he won't necessarily notice that you've arrived in the lane.
Stay positive! 
Use smart cast, watch your mini map. Don't over think dumb shit, ward Barron and drag at all times. Mute your team at the start of the game. Best of luck.
Good mechanics (good csing, knowing when to trade, knowing your champion's combos, stutter stepping, predicting/dodging skillshots, etc) can get you pretty far, easily into gold because if you are the mechanically superior player, you'll win your lane most of the time.
But I find general game knowledge, map awareness, and communication to be just as important. How many games have you lost that you felt like your team had a large lead in? Or how many times have you lost because someone keeps gets caught out? Reminding your team to ward, pinging teammates to get back if they're in a position where they could be caught, knowing good places to camp to get catches, knowing when to group, rotate, or take objectives are all immensely important in getting a lead and keeping it, as well as coming back from a big deficit.
I don't really know what you want to hear. There're a lot of good pro streams for every lane and youtube vids if you want to get good at specific lanes/champs.
