The Non Slip Loop Knot. Superb. The strongest loop knot you can tie. Used by big game anglers worldwide. Easy to tie, far stronger and more reliable than the old fashioned strangulating figure eight knot that can substantially weaken line.
This is a great description with good pictures of how to make a professional wire wrapped loop. Much more stable than a simple loop, especially for heavy beads. Also can be decorative with even more coils.