The Palomar Knot
The best fishing knot I have ever found—for most situations. You can remember the name like polymer (as in space age. It worked for me. At any rate).
A palomar knot is very simple because it's based on a loop or granny knot. Everyone knows this one, make a circle and put your end through. The first knot we ever learn. The palomar knot is tied with these steps:
1. Run your line through the hook eye
2.Run it back through the other way (you can combine these steps by doubling your line and running the bend through the hook eye).
3. Tie a loop knot with this doubled line with the hook or fly in the middle, left hanging at the bottom of the loop. You can tighten this down and you will have a doubled end in a loop and a granny knot on the hook.
4. Bring the remaining doubled end up over the hook (same as pulling the hook through the loop).
5. Tighten by pulling on both the static and loose end. Make sure the loop stays above the hook eye.
A palomar knot holds at 100% of line strength. The only disadvantage is if you have a short leader it will take a little bit more and also because it is so strong, it will not be the breaking point if it is nessacary to break your line, possibly meaning lost gear.
good luck fishing