I always ride alone, pretty much. Even on fairly long rides.
Crow's used to that and listens better to me if we're alone, he gets stressed if we're in a group since he has to make sure that he's not left out :P It's just a training issue, he's not very used to ride in a group but we practice on it.
Also, always wear a helmet. I expect that you do but you didn't mention it. If you fall off and break a leg, you can still call for help, but if you fall off, break a leg and get unconsious, you have a problem.. Having a cellphone is necessary, and keep it well charged. You want to be able to talk to the people you call untill they find you, even if it takes two hours..
If there is anyone at the barn, or just somewhere, tell what road you ride and when you expect to get back. Call if you stay out longer than expected.
I had a friend who used to call me when she rode alone, tell me where she went and when she expected to be back. When she was home she called again. That way, someone would react if she was thrown somewhere, even if it might take a while before I noticed and even if I was in another town at the moment :)