What can I do to prepare my body before getting pregnant

I had a miscarriage in dec my doctor said wait 6months before trying again

Taking at least a few months to heal a bit emotionally and physically is right decision. Allow the body to heal the freshness of the wounds so that body be better prepared for the next pregnancy which is beneficial.
Being healthy and realistic are the only goals you really need to have for this stage. Use the support and take good care of your body and mind.