I mainly use nylon coated wire. haywire twist the wire to attach the fly and melt the nylon with a lighter. This is the approach a lot of big name guys use - like Larry Dahlberg. On occasion I will also use a light wire leader, that you would use with spinning gear. The problem with them is they kink so easy, then your presentation suffers. I also sometimes use single strand wire - especially if chasing saltwater stuff like barracudas that have such good eyesight.

I've used fluoro in the past and have had good luck as well. So you can see I don't have one set approach. One thing about Fluorocarbon is that smaller pike - say 2-7 pounds, can shred it unless its 80-100lb stuff. With big pike and muskies, guys are having good luck (including professional muskie guides) with 60lb fluoro. I've found Seagar to be by far the best. The smaller pike have much sharper teeth. use back to back uni knots to connect the leader to your tippet. Use a loop knot to connect the fluoro to the fly. If interested in fly fishing for muskies, this is an awesome blog - the flies are deadly and interesting approaches/info:

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Hope this helps.

Moonman.