The most important for vegetarians is B12 and protein. After that it will vary by person. I used to track potassium and calcium because of leg cramps. I still track sodium to make sure I keep it low. Women need more iron than men so that might be something for you. The last study I read listed vitamin D as the one more Americans were short on.
Just remember your best medicine is to eat a healthy diet from a wide variety of fruits, nuts, and vegetables.
I've found without question that the best way to lead others to a more plant-based diet is by example - to lead with your fork, not your mouth. ~Bernie Wilke