Want to diversify...need advice.

A good chunk of my portrait business is about to go by-bye.
My business won't go under, but I don't want to stagnate either...
A Walmart has set up shop in our town.
I had two types of clientel here. Those that wanted artistic portraits that Walmart couldn't do, and those that felt the time/cost to drive to the city offset the savings, Walmart offered.
Now that Walmart is here, our portable studio, basic portraits in your home packages is to be no more.
I want to get into Advertising...
Any advice on how to market...Our town is growing rapidly and being the first might pay off.