Hackle quill weed guard
I struck upon this weed guard solution randomly one day because I didn't have anything else to use, and it turned out to work really well! I've never been a fan of mono weeds guards and I don't really think they work all that well. There's only one drawback I've found so far to my quill weed guard, which is that the quill can get kinked if it's bent too far and then it doesn't work as well. For this reason, I tend to use it on flies that aren't very labor intensive, like bucktail streamers.
I'll assume I'm tying a plain old bucktail streamer, though the same basic technique will work on other types too. Start out by selecting one medium hackle fiber from a rooster neck and trimming the hackle fibers off the quill. Then trim the quill, taking off ~1/2" of the thick end and enough of the thin end so the quill ends up twice the size of the hook gap. The quill should be about the thickness of the wire in a large paper clip. I've found that the thick end of the quill really doesn't work very well for this purpose so make sure to get all of the base off until you're at least into the part where it's hollow in the center.
Start the fly by putting the hook in the vise point side up and tying on the thread ~1/2 hook gap ahead of the hook gap. Create a lump of thread, then take the quill and with a couple of loose wraps, secure the end of it just ahead of the lump with the tail end pointing towards the hook bend. Now you're going to kink the quill at the point where the thread lump and hook shank meet. It's easy to do this by tightening up your thread and doing a couple of tight wraps right at this point while pulling on the tail end. Now the lump of thread should push the quill away from the hook shank. Depending on the size of the lump of thread and other factors, the quill may already be in a good position to serve as a weed guard. If it is, give it a few more wraps to secure it to the hook better. I like it to be ~1/4" away from the hook point and to protrude past it a little more than that. This allows for some flex when it hits weeds.
After this, tie on your other materials as you normally would. You can also use multiple quills instead of just one. Tying in two quills at a slight angle on each side of the hook point can also be very effective.
My passion for catching fish is eclipsed only by the fish's passion not to be caught.