Any game involving backstabbing will be your worst game ever. I reached 7th on my previous round because I made an alliance with everyone, and then tried playing them off against eachother, they contacted eachother and got me out before. It's so simple to do, but will cost you a lower place in the rankings.
So what do you do?
Well I don't advise against backstabbing, as sometimes it's needed for you to get further on but I do advise that you don't contact everyone individually as they might be in there own alliances, try one at a time and if they reject, move along to the next person.