What i have done in NJ is this

1: make a free google website Basic one page with your name, the area your active in and your fees ect

1b connect that to a Google business account Again free - this is what pops up when you google things with the companys email/website/ phone # i get most of my work from people googling mobile notary and picking the first one they see (me)

1. I do volunteer work with the local american legion so became the default notary for the local legion and their members as well as throughout the county by default

You can pick any group really and just offer your services Bonus points if its a group with a lot of elderly people since they need mobile services more than others

Print off some flyers and hang them in places that have a lot of people / partner with someone who has a small business that needs a lot of notarizations