I understand your frustration. I'm a veteran moba gamer, I played DotA 1 for 5 years, HoN for 3 years, and LoL for 2 years - and I still get my ass handed to me on a silver platter.
Somethings that are completely out of your control:
1: Their champion hard counters you. You might wonder, I'm playing Blind Pick, what can I do about that? Nothing. There's nothing you can do about that. Don't let playing Blind Pick bring your self esteem down. Because it's any man's game.
2: Now if you want to, try and play Draft Pick. It's like Captains Mode in DotA 2, which personally I believe is the most balanced game mode there is. I refuse to play DotA 2 under any mode other than Captain's Mode, because it just isn't balanced, especially when my MMR is on the line.
Now there are quite a handful of champions you want to ensure are not played in your game, because their kits are ridiculously strong, one could deem them overpowered, one could defend it, blah, it doesn't matter.
#1 Ban
Fizz, at any stage of the game. You do not, under any circumstances want to play against this guy. He can burst you down so quickly, and snowball out of control so fast, that there is nothing you can about it until late game - IF you make it that far. Also, he can tower dive you with no reprecussions because has abilities that grant him temporary invulnerability (or untargetability). For the sake of a legitimate conversation, assume he has Guardian Angel and Repel. - Invulnerability.
#2 Ban(s)
Blitzcrank - Unless the guy is a complete noob and unskilled, he will reign terror on your bottom lane, and your jungler, and whomever he ganks. He has Pudge's Hook, which is generally followed by a knock-up. For arguments sake, assume this is also Devour. Which if he catches you under his tower, it's safe to assume you will not survive.
Rek'sai - He's a new champion to the game, he's kind of like Furion in a sense. His ultimate allows him to burrow to any of his mounds, so if you do happen to have him against you, stand on a mound temporarily to remove it from the game. His map presence is disgusting, and he has some very powerful melee attacks, that will knock you up, as well as deal an obnoxious amount of true damage to you.
Akali & Katarina - Akali is very much like Slark, where she can hide invisible, but she basically has Stealth Assassin's ultimate (the new one), which gives her an additional charge upon a hero kill or an assist. She has very strong burst attacks, with an obnoxious amount of lifesteal (spellvamp). If you do for any reason need to verse an Akali, ensure you have; Ignite, Morellonomicon (Grievous Wounds), Sweeping Lens (Upgraded @ Level 9), or a Pink Ward (True Sight).
Katarina has very high burst damage, kind of like Queen of Pain / Shadowfiend, and if memory serves me correctly, all of her abilities including her ultimate reset their cooldowns upon a hero kill or assist. Some will vouche that hard CC will counter her, I say it's hit or miss. I would counter both of them with Annie if you need to, as she is probably the strongest counter to both. Also note that Twisted Fate's ultimate will reveal enemies who are invisible; including Akali, Twitch, (Unsure if it does Shaco).
Yasuo & Zed - AD Assassins much like the above, except AD. I think Yasuo is one of the only champions in the game aside from Galio who can pull off an AoE disable, resembling much of DotA's team fight disables. They are both very mobile with their abilities, and Zed is "kind" of like Fizz, as he can tower dive you, generally without punishing himself in any way.
#3 Ban(s)
Lee Sin
Kalista
I could go on, but my match is about to start.
