Lifestyle, timing. As far as things you can control - if you smoke, stop smoking, avoid caffeine and alcohol, and try to maintain a healthy weight (bmi of 18.5-25). Reducing stress can help as well. Also remember that a woman's fertility declines with age. Having regular intercourse (2-3x/week) or timing intercourse around ovulation will increase chances of conception.
It depends. Depending on your age, how long you've been trying and whether or not you have suspicions of problems in certain areas (sperm, egg, tubes, uterus), your best strategy may be to patiently keep trying or to explore some medical assistance. More information is needed to guide you specifically.