Does anyone know of anything that I can do so that I ensure that I get pregnant?

No, it is never 100 percent,

Unprotected sex at the most fertile time of the month done by tracking your system.

It can take on average it can take a couple a year to get pregnant. How long have you been trying for?

For some people, getting pregnant is not as easy you may think.
You're more likely to get pregnant if you and your partner are both in good health. Perhaps you can make some changes to your lifestyle, to improve your chances of getting pregnant and having a healthy pregnancy.

Being overweight or underweight can affect your chances of conceiving. Too much or too little body fat can make your periods irregular or stop them completely, which can affect your ability to conceive.

When you're trying for a baby, avoid drinking alcohol to reduce the risk of harming the baby. If you choose to drink, you should drink no more than 1-2 units of alcohol once or twice a week and don't get drunk.

You're most likely to get pregnant if you have sex within a day or so of ovulation (when your ovaries are releasing an egg). This usually happens about 14 days after the first day of your last period.
An egg lives for about 12-24 hours after it's released. For you to get pregnant, a sperm must fertilise the egg within this time. Sperm can live for up to seven days inside your body.

If you have been trying for 1-2 years without success, see you doctor for advice, to rule out anything that could be affecting your chances of concieving.

Good luck