It's okay to attempt to create a work that has wide appeal, but keep in mind that in trying to appeal to everyone, you are diminishing your comic as an art and risking it becoming more of a product - or maybe in a simpler way of saying it, if you try too hard to appeal to everyone, you will lose the soul of the comic, the thing that makes it intriguing and honest.
I would say the best way to go about this is to identify on already existing aspects of your comic which you find appeals to certain demographics, and then focus/capitalise on it, depending on what direction you would like the work to go.
Good luck 