Really depends on your community, I opened an ice cream shop because they only have soft serve here. I know for a fact there are other demands that need filling in my area. I don't really think it has to be liberty oriented, however liberty minded business owners should be more passionate, there are so many things to choose from. Also remember that a little bit of competition is good, but a flooded market is not. Good competition drives up quality and lowers prices in a marketplace.
Don't focus on changing people's minds solely for the cause of liberty. People will fight against you.
One thing I learned in psychology is a stronger frame takes over weaker ones, so if you are doing well, or have a good reputation someone else who isn't doing as good as you are, will latch onto you. Simply telling someone you own your own business is enough to get respect in most situations. Those with "worker mentalities" will listen to you talk about liberty and accept and become what you believe with little to no arguments, simply because you are more accomplished than they are.
If you want to change minds and hearts, you must first be a leader, just be the best person you can and lead by example. People will follow.