My preferred method

-1- Tie a figure 8 knot on the very end of your halyard.
-2- Grab the halyard ring and loop the halyard through it
-3- Bend the halyard around the part that is vertical and that is just before loop around the ring.
-4- Put the end with the figure 8 knot under itself; the part that is between ring and the bend around the halyard.
-5- Tidy the knot up by sliding all excess line out of the knot so that the figure 8 knot sits next to the halyard itself. So that is actually rests on the halyard itself

In fact this knot is very close to a simple hitch. The working core is the figure 8 knot. This prevents the hitch from becoming undone under tension. This knot is very small and easy to undo even after it has been under alot of tension.

NOTE !!

Make sure that the side the figure 8 knot is on (pointing to) is NOT the side on which the halyard is passing the hook up the mast. If this is the case that the knot will prevent the hook from engaging easily. So if the halyard runs past the hook on the left then have the figure 8 knot point to the right. In this case everything should be rather easy.

Wouter