You find an INFJ when he decides to show himself to you. Mwahahaha.
But seriously, grocery shopping, bookstores, quiet stretches of land, parks and libraries. I also like meeting friends of friends. People I know know what types of people I like. I don't mind people coming up to me if they seem friendly and motiveless.
look for aux Fe being surprisingly disarming when engaged and look for the Ni stare. the Se sensotard moments helps too, sometimes injs look like little children when they walk with their arms hanging down.
we look serious, but Ni doms start thinking overdrive and you can see it, the horsepower underneath the hood.