Bead tips provide an elegant way to hide knots at the ends of bead thread. To use a bead tip, thread the end of your stringing material through the hole, then knot it in the "cup" to secure your strand. If your thread is very thin, you may want to tie the knot around a seed bead, for extra bulk and security. Next, fold the rounded halves closed, to hide the knot. Next, bend the hook closed to create a simple loop, and attach a clasp or jump ring. The loop on extra-secure bead tips is already closed; use a jump ring or split ring to attach a clasp.
What's the difference between bead tips and crimp beads? Crimp beads are crimped onto beading cable or wire (they're best for stringing materials that can't be knotted), whereas bead tips are best for thread and cord that knots well (and might get cut by a crimp bead). Bead tips aesthetically hide the secure hold created by the knot inside them.