I candled the eggs to look for larger veins. Used a razor blade with most of it wrapped in a think layer of electrical tape. The only exposed part of the blade was almost the same size as the thickness of the egg. I pinched a portion of the egg and made the cut. After the initial cut and seeing exactly where the baby was I used very small scissors to cut the "V" shape.
Of course I have the very limited experience of only cutting one clutch. I did clip some veins, but didn't have any issues.