Mumujan - Access the GhostRatings list to get a general idea of the best players on the site.
This is the GR page where you will find some info about what GR is: http://tournaments.webdiplomacy.net/theghost-ratingslist
The October 2014 ratings are at: https://drive.google.com/file/d/0B_KSmWyLiG1pSWdQNGVCSUVPNUU/view?usp=sharing
To play the top ranked players:
a) PM them directly and request them to join a game with you or let you into a game
b) Join games with a minimum of 50-100

- they will invariably have some good players in it
c) Take the slow route, build up a good record and reliability rating and eventually people will start approaching you
Also - completely agree with goldfinger. The top players are all the best, most trusting partners....for a while. The aim of the game is to work together and be trustworthy yes - but the aim of the game is also to win - so at some point the trust has to be broken. Sacrificing a win just to maintain loyalty through to the end is against the spirit of the game - I'm sure most people will agree with that and not just on this site.