How must I select eggs for best health?

Possible. In our experience, by doing pgs, or checking each embryo to make sure it is chromosomal normal not only improves pregnancy rates but decreases the risk of a miscarriage. Although some clinics disagree with this, our data definitely supports the increase pregnancy rates and decrease miscarriage rates with chromosome testing. Also, emotionally, you know that you transferred normal embryos.
You can"t. Natural conception itself is terribly inefficient with 20-50% of pregnancies miscarrying ivf and embryo selection is closer to selecting the best eggs ivf-pgs ( genetic testing) is the next best way, but may injure an embryo... So careful patient selection is paramount!