Artificial Insemination of cows is a great topic and one which there are many options and NO TRULY GREAT ONES, IMHO.
I like CAB's plan, but in my situation, I run 25-30 brood cows and a Gomer Bull with Chin Ball is too costly to carry.
I have used "Observation for Natural Heat" twice a day however, it is extremely time consuming (if you have the time). Also, the evening observation is my favorite but hard to accomplish with kids and/or grand kids in sports and school activities, as well as your own evening meetings and social events. When done in a timely fashion and not missing "observations and breeding's" it has been my best percentage of service-to-bred A.I.
I like synchronization protocol the best for having an actual "start of calving date" with a group of cows and not just one or two here and there over a 21 day window while getting a chance to service all of the cow group. Thereby shortening my A.I. calving time. It allows me the dates to get help for working cows. It allows me to breed on weekends when I am home and/or is an easier time to get help. However, my conception rate on synchronization groups has not been satisfactory or high enough on a year-in-year out basis and I have been using synchronization for quite a few years and quite a few protocols (working with a cattle repro vet).
What works best?