One trick I've used for ages is to use two strands of floss to mount a bead and create an cross stitch when placing bead. First half of cross stitch is with the bead the 2nd cross of the stitch is then put over top of the bead making sure one of the two strands of floss goes over either side of the bead... This ensures that it stays in place firmly.
If you are only able to get one strand into the needle that you are using you can then pull the thread through to even up the ends and use the double thread to stitch with... I do this most of the time with noraml stitching aswell. Save the thread from constantly pulling out of my needle as I stitch too.