1. Start with the bowtie lying face up. Adjust the bowtie so right side is shorter than the left. The end on the left will be referred to as A and the end on the right will be referred to as B.
2. Move A to the right side, across B.
3. Bring A under B and up through the neck loop.
4. At the joint, fold B towards the right and then towards the left to create a the bow shape.
5. Bring A stra­ight down over the middle of the bow shape that was made with B.
6. Fold A back towards the chest and pinch the fold.
7. Push the pinched end (A) through the loop behind B.
8. Pull on the folded parts of the bow to tighten.
9. Adjust until balanced on both sides.


Source: Ties.com