Originally Posted by
Sivalion
YOU SUCK AND YOU BELONG WHERE YOURE AT.
Kidding, obviously!
First off, positive attitude is key. If your teammate fucks up, simply tell him "hey friend, can you please group up?", "hey top, can you please ward your lane? if you need help at warding it, let me know and I'll chip in", "please stay grouped so that we won't get caught!" and so on, don't sound negative and just tell him what he could've done better - however, dont try and tell them not to miss skillshots (although realize that half of the community are a bunch of spoiled brats who cant differentiate(?) between positive criticism and blatant flame, just shrug it off and move on if they wont take your advice) and such, it happens and generally you'll miss more than 50% of your skillshots which is normal for everyone, better throw too many than too little.
The thing to remember is that the only difference between Diamond and lower Elo players is their knowledge of the game and in-game mechanics, this means knowing when to build what, knowing who counters who, which lanes to help early, when to go aggressive, when to splitpush, go defensive and all that, all this comes with time and experience.
As I main jungle myself I can only really go in-depth with that (if you want to know, say so).. but I do play a cool mid aswell, the thing about soloqueue though is that you have to adapt to everything, as opposed to premade teamgames where the game is more defined, in soloqueue you constantly have to look at how the games going and go "alright, top's feeding, gotta gank his lane a few times so we wont fall too much behind" and so on - know when you can and cannot gank (ex if top has a huge wave at his turret, ganking might not be a great time, but realize that the wave will most likely soon be reset, so stay nearby), help your jungler counterjungle, make the calls, force plays in their jungle if you're confident you can come out on top - it's all about making plays snowballing the game to your advantage, and try not to do too risky plays (such as diving unless you're reallllyyy far ahead).
roam, ward, collect Elo
as Zariay said, if you feel demotivated, down or just sad.. take a break, have a shower, go for a run, take a trip to... palm-dale.. relax for half an hour or even an hour and come back motivated.
watch replays of your games, analyze them and point out your own mistakes to yourself.. "okay, if I'd ganked bot often instead of doing X then they might not have snowballed on us...", "if we didnt go for X objective then..." you get the point.
i'm current sitting in plat 5, have jungled against diamond 1-challenger teams and have fared pretty well against them, I'm not pro but I know my stuff.
PS: i havent slept yet pretty tired so sorry if things are clumsy, if you're unsure on something ask and i'll elaborate.. it feels clumsy as fuck when I read it back >.< fuck