Take a look at these lovely beaded ornament hangers. They are my favourite so far, and I'm not taking any credit - it is ALL about those gorgeous red beads. I think they look for all the world like maraschino cherries as they are similar size. But please, don't eat the cherries, these go on your Christmas Tree.
For the rest of the beads, I prefer to use a mixture of 6.0 and 8.0 seed beads as it adds a bit of texture - but it's not necessary - you could use one or the other. I do recommend though that you create the focal point at the bottom end of the hanger - this will ensure that it hangs below the boughs and draw your eye to what's important - the ornament itself.