Go to all the local bike shops in your area and figure out the size frame that fits you(they’ll let you try out the bikes).
I definitely recommend against getting a mountain bike unless you plan on doing mountain biking (which is a lot rougher than biking over dirt paths here and there). If you’re new to biking and want a bike that you can do some city riding in AND hit up a few dirt paths with I would recommend a hybrid bike with suspension (not any hardcore suspension, though- very low travel suspension that won’t compress a whole lot and slow you down when you’re on the road).
Other than that it’s just a matter of trying out different bikes and seeing what you like. There are a million opinions as to what bike to get but basically anything from a local bike shop will, for the most part, be a reputable brand. (And by local bike shop I mean eaxclude department stores that sell bikes).
Good luck!