I hate those little tails that hang off of bobbins. I bought a package of hole re-enforcements and put the "tail"on the top (flat side) of the bobbin and then put the re-enforcement on top of that. I also write 100% cotton on the re-enforcement so I know which thread is in the bobbin. If there's nothing written on the re-enforcement then it's not 100% cotton thread.
I also took a sharpie and marked on two of my bobbins so I'll also know if the black or white thread that is on the bobbin is bobbin thread for embroidering.
Thanks everyone for the great suggestions!