I think GMs should not be seen unless needed, should not "make things happen" unless it's to fix something, and that they should have the world running to the point where players don't even notice that the GMs aren't holding their hands through everything.
In other words: A GM should NOT be needed every second of every day, because they should have the world running correctly to begin with.
They should be in the background, making things work, keeping everything in working order, and making the world playable.
A GM should *NOT* give a player anything just because the player asked for it (Hell, I refuse to give my nephew something as simple as a hooded shroud of shadows). A GM should *NEVER EVER* give his own non-GM characters *ANYTHING*. A GM should not allow a player he or she is friends with get away with anything other players would be punished for. A GM should follow the shard's rules even more than the average player (No point in having rules if the rulemakers are going to break them)
A GM should also NEVER in any way punish a player "just cuz they don't like them" or they disagree. It's not fair to the player. If you disagree with a player on something (Not rules related, of course), let it be. Everyone's entitled to an oppinion. Don't hold a grudge. If the same player is stuck somewhere because of a problem with the shard, don't sit and laugh and let them get killed or whatever. Fix the problem.
I could go on, but I think I've spammed enough ;->