What can be done to keep my quiche from separating?

I find mine stay together better the more they are blended. I've actually taken to using my immersion blender to really beat the eggs. Then straight into a hot oven.

Be sure to saute and drain any vegetables before using them in quiche to eliminate as much extra moisture as possible. You could also try adding an extra egg or two, or using a higher fat milk if you're using skim or 1%.