when we decided to "go for it", i just went online and found an "ovulation calendar"... i typed in the length of my cycle (if you know it) and the start of my last cycle and it told me the best days to have sex. i made sure it happened on those days and voila! i was pregnant that cycle.
BUT, while it was easy for me, others are not so lucky.
i DO believe:
1) some women have a hard time getting pregnant
2) some women have a hard time staying pregnant (recurrent miscarriages)
3) some women have a hard time being pregnant (very complicated pregnancies, emergencies that crop up, health issues etc)
i fell into #3.