Sylph.Decimus said:
Easily the best way to cap it for me (as 75 thf) was to go to Meriphataud Mountains (S). It's been a while, but there is a single Yagudo Sentinel between this one passage as you head SE from the northern entrance.
I think it's the passage where you can cut through the mountains from west to east as if you were going to the Sanctuary. Anyway, the Yagudo is 76-78 and you can hide and it's a monk. It's easily the fastest skilling up I did.
This is my method, too.
Also what's important to note is that you can Hide from it. So I run up on it, hit Steal to draw its attention (and maybe get an item), then run circles around it until I get red HP. Then I pop Hide, go heal up and, when timer is ready, repeat.