First child at 38 -- advice needed.

❤️❤️❤️ • FTM, baby girl due 11/28/16.
My husband and I got married a year ago and have been TTC for a few months now. I cut my alcohol consumption to one glass/week, eliminated caffeine, and made my hubby take zinc and a multi-vitamin daily. All that and a yoga shoulder stand after we did the deed on the days pinpointed by the <a href="https://play.google.com/store/apps/details?id=com.glow.android">Glow app</a>, and it worked. We just found out I'm pregnant!  
​Of course, it's really early right now - I'm only 5 weeks, and we are really superstitious and cautious esp since I'm older. What can we do to prevent a miscarriage? I don't want to do anything that could jeopardize the baby's health.