Rambo,
I'd have to agree with Gnu Bee Flyer's post. It would be very helpful if we knew what type of fish you're going to target and what type of waters. You're going to get many posts on this one. For me, if I'm fishing a small trout stream I'll use a 7'6" leader and add 18" of tippet material. I attach a 6"-8" of Amnesia Running/Shooting Line to the of my fly-line. I'll attach the leader to the end of the Amnesia, and tippet material to the end of the leader. I'll attach the Amnesia to the fly-line with a nail knot. I'll attach the Amnesia to the leader with a nail knot with 3 wraps on both ends. I'll attach the tippet to the leader using a double surgeon's knot if I use monofilament or a triple surgeon's knot attaching flurocarbon tippet to my leader. I've also started to use Frog Hair Running Line in place of the Amnesia because it's just as strong but much thinner. On large rivers I'll use 9' leaders and add 18"-24" tippet material. This system is used on floating fly-line. As for leaders and tippet material I've been using Climax for years but I'm in the process of switching over to Frog Hair. Just my $0.02 worth. Good-luck!