HELP!!

My husband and I have been trying to get pregnant for a year now (it obviously hasn't worked). Is there anything I can do/try to boost fertility or boost chances of getting pregnant? Such as certain foods I can eat or need to avoid, certain positions, or vitamins I can take?? We both have children (I have one and he has one) by other people, both 6 years old. So it's been a long while since I've had a baby and my son was very unplanned. (I was 17 when I got pregnant.) Any advice??