Theres no rules for seting up the limiter, only guide lines. You basically want it to grab the fast peaks that occur and tame them down. Try a high threshold with fast attack and adjust the release time according to the music.

http://www.theprojectstudiohandbook.com/articles3.htm

There is a difference between limiting and compression .... so let's be sure that limiting is what you want. Limiting usually uses ratios of 8:1 or higher with a fast attack and release while compression employs ratios lower than 8:1 and may use slower attack and release settings. Typically, the practice is to set the threshold of a compressor or limiter for a gain reduction of (at most) 6dB. There are situations where you may wish to reduce the gain by even more but at gain reductions of less than 6dB, you can compress or limit more transparently without as many audible effects. I often will compress a little while tracking and then a little more at playback to keep a lid on things without making it sound so squashed..