I actually got pretty lucky and doing my first route shopping. It's not out of the city per se (I'm in a VERY BIG CITY) but it involves nearly 150 miles.
I'm in my 2nd month of shopping and though I'm still brand new, I have learned quite a few things from people here on the forum and through my own experience. Like Lisa, when I started getting great reviews on my reports consistently, I would respond to schedulers right away and let them know that I was available and also my preferences. But it's in the form of, "Hey, if you need anyone to cover a few shops next week, I'm available!"
I am still not in control of my schedule quite yet as I'm trying to still work my way up the ranks and get at the forefront of shops versus waiting for the apple to fall. However, I've broken in with a few schedulers and been able to map out a few good routes which usually takes awhile to do.
Part of it is luck - as shops need fresh faces to cycle through rotations. I probably was at the right place at the right time as well not having too much scheduled in when they needed it.
However, I'm still very new and I can't juggle too many different types of shops. I mix in a few types of ones I have done before but I get overwhelmed to do a retail, restaurant, service, and fast food all in one day. I would have a heart attack! Find the ones you do well and are comfortable with and let your scheduler know. Also, when you see the schedules, keep an eye out for location. Maybe you won't get it this week or this month, but plan on the next month!