i used uncolored, undyed cotton thread from my moms sewing supply stash. I read that it usually deteriorates by the time the roots take hold so basically, no cutting or ugly rubberbands. A lot of people use fishing line, and stuff as well!:biggrin:
I've used small hair ties that don't have the metal clip. While I'm sure that there are better solutions (the cotton thread sounds the best to me) I felt too lazy to actually bother to do that. The elastic keeps a good hold on the plant, but you can still move it if you want or need to. Also, the elastic eventually weakens, so I just break it to remove it.
Like I said, not the best option, but it's what I do.