Been plat for S2 to S5, really want diamond this season, how can I do it?

I may not be at the rank you want to reach, but my best friend whom I duo with all the time has been stuck in plat for the past two seasons as well, and so I will give you the kind of advice that I would give him (if he weren't so gosh darn stubborn :P )

Firstly, whatever it is that you do, find ways to make what you do safer. If you tend to split push a lot, make sure you have consistent ward coverage in the enemy jungle so that you get more prior warning when you are getting ganked. If you're a jungler, make it a habit of predicting where the enemy jungler is, and where they are likely to go. etc. etc.

Next, work on refining whatever it is that you do, and try out new things. Try different strategies and different build paths. Heck, even try out some different champions from time to time if you've found yourself using just a few predominately.

Additionally, see each game as a chance for improvement, and a chance for learning. If you take the game in this manner, then you should be able to improve enough to make your way to diamond.

Lastly, play in such a way that you win games, not that you don't lose them, if you catch my drift. You want to be an active positive force on your team, through which your team wins. The best way to do this is by becoming an active shot-caller and telling your team what you want them to do. As someone who has been playing from either S1 or S2, you definitely have enough experience with the game to assume that role.

Sorry if the advice is a little vague, it's difficult when I know so little about you. For reference, I'm a S1 player myself, so I'm not just pulling stuff out my behind.

How have you not hit Diamond yet?

I didn't finish placements for S1, I wish that I had, but I didn't. S2 I was Bronze (best Icon ever other than S1 Bronze) S3 I pushed myself to hit Gold in the last month of Ranked (I was so proud of myself) S4 I pushed myself farther into Gold to hit Gold 3. S5 I pushed even harder to hit Platinum because I wanted it. S6 I started Gold 5, but I'm going to hit Diamond this season because I WANT IT.

If you want something, put time and effort into it. Also, the advice that Shiroi Kitsune is giving works too. :P

Hello there, ended last season plat 1 but was diamond 3 times throughout the season (got demoted twice and Ranked Decayed the last time) and my opinion on getting diamond the easiest way possible is to basically One Trick Pony. I got diamond spamming Kat last season and plan on spamming Ahri to diamond this season and it really is the easiest way to climb. You can really define the strengths and capabilities of the 1 or 2 champions you choose and know how to win with them.

Also try not to die, sounds simple but its pretty important. Watching people dive 1v3 to pick up that 100 health opponent is not worth even if they pick up the kill. They effectively took a 4v5 (the low health enemy would need to back) and turned it into a 4v4.

So thats my pretty simple advice as someone who hit diamond last season a few times on the easiest way to climb. Find 1-2 champs for the 2 dynamic queue roles you pick and play them very well (choosing champs that don't have horrible matchups is a good idea) and try to die as few times as possible.