When I start to embroider beads onto a doll, I like to place accent beads for interest. In this case I will use flat Paua shell beads for the mermaid's tail. I use E6000 adhesive because it dries clear, and has enough body that it holds the item in place without slipping as it dries. It is important not to apply too much, though, because you don't want it oozing around the edges of the accent bead. This will make it really difficult for a thin beading needle to pass through.
I apply the glue with a toothpick, not by squirting it directly onto the accent bead.