As long as we remain in samsara, killing is unavoidable. Understanding this should increase our determination to abandon samsara; increase our bodhichitta; and thereby energize our efforts to realize the correct view of emptiness.
We would go mad trying to figure out how to completely avoid killing. Mainly, we need to abandon the intention to kill, and strive to minimize our relationship to killing. We kill by moving; by not moving; by eating; by not eating. Millions of living beings are killed in farming vegetables; millions are killed when one animal is slaughtered; the delivery planes and trucks kill many living beings delivering the food; we kill many living beings driving to the grocery store. You see? Samsara is the real problem here, and escape is the only way to really abandon killing or liberate others from suffering. Changing our intentions is the main practice.
Whether we are vegetarian or not, whether we purchase meat or vegetables, death has occurred so that we may have sustenance.
However, however, that said, it seems to me after much consideration over the years that with respect to eating, the best way to avoid killing or excessive deaths would be to only eat nuts, seeds, vegetables, and fruits that we grow in our own gardens, and to try to purchase products that have the least negative impact on mother living beings. If we take the time to do the research, we could come up with this kind of meal plan/diet, and following it would become second nature.
We do not need to eat meat. We also do not need to eat vegetables and fruits that have been farmed as it involves excessive killing. Anyone who's gone to the sink to wash a head of organically farmed lettuce will see how much suffering there is. Sometimes there are still many living beings crawling around on it or disabled in some way due to the processing!
Thanks to everyone for the wonderful posts. Time to realize emptiness eh!