I'm with Mona on Main st. It's easy and everyone expects it! Unfortunately, there are more than one "Main St." I have found in the same city, there are things such as Main St., Main Place., Main Ave., Main St. Ave. E. Main St. W. Main St. SE Main St. and .... It's very confusing sometimes! Hahaha! I hope you don't get lost, just always keep your mind "Mainly on the road!" :)
Main street is very common. But you won't see a first street, only second and higher. That's because first streets were changed to main streets as the town grew and that street was the "main" ones used.