hi! I used and OPK and got pregnant the first try. I had good luck and they were very inexpensive. They have very good directions. I had just gotten off the pill, so I was really using it to see if I was ovulating. The best advice I ever got that worked the first time was to make sure you don't wait until the day you ovulate to begin ttc because it seems to be too late by that day. OPK's are good because they measure a hormone that is present in your urine 72 hrs before you ovulate, so you can start then and give the little swimmers a head start. Like I said, they work for me, first try. Best of luck to you and baby dust!!