All the old ones I used are down. Does anyone know a site that is up?

The best sites are probably alliances sites. You can join an alliance by making a post on the alliance talk forums, and I'm sure lots of people would be willing to mentor you and teach you some of the new stuff.

best and nearly only option is to join on some alliance on alliance or ffa server and that way gain access to strategies.

if you ask what's best alliance to join then laf and evo have won total and average networths many times and apparently have good tutors but its up to you where to join.