I just reached Gold and here is how I did it:
* Don't play solo ever. The chances of you getting unranked and horrible teammates are really high when you rank alone, and you will face premades of 3-4 that are more coordinated than your team and likely with a smurf (I will explain below)
* Play with smurfs. The only way to climb consistently is to have a smurf in your premade. Every premade has some sort of smurf nowadays, either that or awesome skype/discord coordination. Are you one of those who have their buddies in coms practicing and understand each other? If you aren't then your only hope is to queue with a smurf.
* Chinese players are your friends. There is a huge influx of Chinese players into NA servers for some reason, they have played in the Chinese servers (which I heard are full of cancer) and know a lot about the game, if you see a Chinese player then its your best bet because they play at gold skill lvl while being in silver or bronze.
* Avoid Unranked at all costs. Unrankeds are the worst plague you will ever see in your ranked matches, they are fresh out of lvl 30 or they have never played ranked before, in any case they will play like its normals and don't give a care in the world. If you get one of them either dodge or make them dodge by banning their pick.
* Always run a background check on your team. Check what champions are they good at and what champions are they bad at, if they are just picking a champion because is "fun" but in his record its full of 0/69/0 then just ban his champion and hope for the best. Remember that AP rengar that went 0/7/2? That shaco support? that nunu support?
In other words don't be afraid to be boosted. Honestly this is the only way to climb consistently nowadays, every tool Riot has put at the premade disposal is against the solo player, don't be the solo player, Riot doesn't care about you so you must work around their shitty system.