A tip for those "unwinnable games"
This is something that I picked up from Foxdrop, but thought I'd drop onto the forums since I've seen a lot of my "unwinnable games" become 50/50's based upon this principle.
Basically, the idea is that every game is an individual game and needs to be looked at as such. It doesn't matter what the meta is, or who is on your team. Take a look at your team and figure out your win conditions. 5 ad? Realize that your going to be a lot stronger early-lateish mid, but will fall off sharply when the enemy team gets enough armor/health. Realize that a full ad comp is going to be ridiculously quick taking objectives, but not going to be too super in team-fights (unless ahead). Objectively speaking, full ad comps are horrid since they're super easy to itemize against, but if you know your win conditions, you can play off of them while avoiding your weaknesses. This goes for people picking "troll champs", getting countered, etc. Just realize what you need to do in this individual game and work from there.
In addition, remember that you should not be focusing so much on winning/losing when you play ranked, but rather should be looking for ways to improve. Miss a drag last game because you weren't paying attention to the timer? Make sure you always know 60 secs before hand when the drag is spawning this game, etc. When viewed in this way, you will realize that even if a game is completely lost from the beginning, you can still get something from the game as you will improve yourself, and be able to bring that improvement into the next game.
Anyways, that's just something I've found that's been quite useful for me. Hope it helps you all on your journey upwards.