You must check your fertility signals to find out when you ovulate each month. Your cervical fluid will tell you that you are "approaching" ovulation. By checking your morning temperatures, you will confirm that ovulation indeed past.
To confirm that ovulation has past, you need to take your morning temperatures every morning before getting out of bed and observe at least a .2 degrees shift up in temperatures than any of the last six temperatures before it. My pre-ovulation temperatures usually run between 97.0 and 97.9. After ovulation, my temperatures usually jump up to between 98.1 and 98.4. You have to find out what's normal for you, but my temperatures are pretty "normal" and can give you an idea.
To achieve conception, strategically time intercourse to occur at least every other day during your "fertile" window and on ovulation day. In order to keep up with this, you must chart your findings on a fertility chart.