Ok, I'm totally new to fly fishing, just got my first combo together today, goin out practicing casting for the first time tomorrow, and I noticed that there is a taper on the leader that came with the reel I bought. What I wanted to know was how much of the leader should I cut off through changing flies, getting snagged, stuff like that, before I put on a new leader. Sorry if the question is confusing, I'm not well versed in the lingo of fly fishing.

I'd like to suggest a great fly casting DVD for you. "Basic Fly Casting" by Doug Swisher. It's a Scientific Angler's DVD. You can order it online from BPS. Great instructional DVD.

As soon as I get into the thicker diameter stuff I change my leader, but even at that, sometimes I just tie on longer sections of tippet to accomodate.

When a leader is fresh, I usually go with about a 3' length of matching "x" tippet to the leader. Meaning, if it's a 4X leader, I'll add a three foot section of 4X tippet. I then add about a 2'-3' section of 5X tippet to that.

Ultimately, you really don't want to go too far into the thicker diameter stuff on the leader. It'll effect both your fly drift and to a lesser extent your casting roll.  The former, in my opinion, being the more important of the two. 

Hope that helps and good luck!

Also Make sure you have a leader straightener, This is basically two flaps of leather connected at the top with a rubber type liner inside. you run your leader through a couple of times and the friction creates a little heat that straightens your leaded. This will help your leader and fly to lay out in front of the fly line instead of piling up in a big coil. good luck and practice, practice and practice some more. the one thing that helped me is to practice those short under 30' casts until you have confidence in the short game and then you can get more ambition.

Brian

I have read much and have been fly fishing for a few years; here's what I know.  Barely cut any off of the leader, you want it to stay long.  Go to your fly shop, or Bass Pro shop nearby(they have a fly shop) and ask to buy 'tippet'.  Tippet is to be even smaller in diameter than the leader, and is the area to tie on the fly or cut off flies.  When the tippet is cut all the way back to the leader, retie more tippet.   Have fun!

you can also use regular fishing line in the proper diameter tippet materail just makes it easier. I like diamond rio for the most part,

When i got into fly fishing, i jumped in with both feet. I learned new knots, tied my own flies, and tied my own leaders. I ended up spending so much time doing the tying, i never got to fish... The Leader formula i used is what I learned at Penn State (yes, i have one college credit in fly fishing). It is George Harvey's formula as taught by Joe Humphreys.

From line to fly: .017(15") / .015(15") / .013(15") / .011(12") / 2x (12") / 3x(14-18") / 4x(14-18") / 5x(20-36")

The last three sections are adjusted to your current situation. If your fly is falling on a pile of line, shorten the lengths. This will in effect stiffen the leader. Consequently, you don't want your tippet and fly to fall in a straight line, either. If so, it will begin to drag immediately. Your tippet material should have soft 's' curves leading up to the fly. These soft loops will act as a sort of shock absorber and not let the current drag on your line affect the float of your fly.

Since i've gotten away from tying my leaders, i've been buying 9' tapered leaders in 4x. I tie on the last bit of 5x. If i'm using streamers or weighted nymphs, i'll just tie on more 4x. I like the flourocarbon tippet materials for subsurface patterns since it is less visible and sinks better than mono.