This knot is popular among sport fishers for the same reason why bridges use steel cables; it is incredibly strong. In order to tie this knot successfully, keeping its strength, one must remember to keep the lines tense, if you don't, you will get a weak knot that may end up slipping. Of course, once you get the hang of this knot it will be that much easier to make for your future fishing trips.
How to tie the FG knot:
1. Have a way to get tension onto your braid. We need tension so we can essentially wrap and thread the leader onto it. The easiest way to get this tension is to lean the rod away from you.
2. Hover the leader over the line. We are going away from us first towards the rod.
3. Open the loop and go around the line one time.
4. Alternate the loop but this time going towards us.
Continue doing this looping motion, looping away from us, and then towards us, for about twenty loops. The knot must be done with tension on the line so make sure you keep this tension.
After you've looped the FG Knot for about twenty times, you need to lock it in place. Now you can remove the tension off the line and you will need to do two hitch knots which will wrap around both the braid, and the leader. Now pull the two main lines tight making sure the knot does not slip.
The final step is to trim the leader and make sure the end won't catch on the rod. If you think it will, make a couple more hitch knots.
You now have the strongest knot going from braid to leader.