We also faced such issues but then it became difficult for us to survive such a situation. You must chose to eat healthy diet on regular basis. Stay away from unwanted drugs. Consume folic acid in your diet will help in you much before the conception has occurred. Make sure that you manage stress well.
I was also scared about miscarriage as my pregnancy was much complicated. Weight control also helps in preventing pregnancy miscarriage. Healthy diet and taking folic acid helped me a lot during my pregnancy.