My advice would be to read posts by:
Praying Mantis
Jason Strasser
Bozeman - warning: Math intensive
Eastbay - warning: Computer modeling intensive
William - warning: you will have to sift through lots of idle chit chat, flame wars, and humour to find the nuggets of wisdom
Outside this forum, Great posters include:
Fossilman - lots of multi advice and tourney theory
Davidross - his playing online for a living posts are pure gold and should be made into a book
There are others of course... Clarkmeister, Dynasty, Ed Miller, etc... I'm sure I'm missing a lot. The above are my favorites though
My Threads are not bad either and I wish I could take the credit for that but the truth is I just like to get in on great threads. I also like to get answers from great posters so you can find some good stuff 'around' me a lot.
As far as how 'good' players actually are, who knows for sure. I think I probably wouldn't be far off if I said Strasser or ZeeJustin are our resident 'best' SNG players. That of course must be accompanied by the caveat that they play 200+15 so a LOT of what they say will get you in trouble at lower stakes.
Check
this out before you search around too much
Regards
Brad S
Edit: I can't believe I almost forgot about BruceZ. Everything you ever wanted to know about Math