I use weed guards on some of my saltwater flies. Right now, I am using a short piece of 20# fluorocarbon extending from the head to just beyond the point. I have tried to find a stiffer, lighter line to use with no luck. Here is an example, but in this picture I haven’t timmed the end of the guard.

I have also tried tying in a piece of light fluorocarbon at the bend of the hook and looping it under the point of the hook and tying it back in at the head. I have had problems with this arrangment fouling and interfering with hook sets.