The key to getting pregnant is having sex on your most fertile days to conceive a child.
That makes sense, of course.
There is only a small window of time that you can get pregnant each month.
The hard part is trying to figure out which are your most fertile days.
Since every woman is different, it can be hard to tell.
What this means is that you have to try to figure out the exact day that your ovaries release the egg.
This is the time when you can get pregnant.
Sperm can live in your body for a few days, so your most fertile days are the ones leading up to the day that you ovulate, the day that you ovulate, and sometimes the day after you ovulate.
There are a few ways that you can figure out your most fertile days to conceive:

1. Tracking your menstrual cycle.
   If your cycle is very regular, you can estimate that the day that you ovulate is 14 days before your period.
   The time between when you ovulate and when you get your period is called the "luteal phase" and it varies from woman to woman.
   The average is 14 days, but your luteal phase may be shorter or longer, so this isn't the most accurate way to tell.
   
2. Tracking your basal body temperature (BBT).
   Immediately after ovulation, your body will have a sharp increase in temperature.
   You can measure this with a basal body thermometer--a regular one isn't sensitive enough.
   Unfortunately, the spike happens after you have ovulated, so you have to track it for several months before you'll be able to predict when you are ovulating.
   
3. Testing for luteinizing hormone.
   This is the hormone that tells your ovary to release the egg.
   You can purchase test strips that test your urine for the hormone.
   Test twice a day and you should be able to catch ovulation.
   

Even though you may have sex on your most fertile days to conceive, you won't necessarily conceive a baby this month.
The average couple takes about six months to conceive a child and it's not uncommon for a couple to take more than a year.