I usually ride alone. I will only do trails I know, so if there is something new to try I will wait for a riding buddy to try it with. I always carry a cellphone - even if reception is spotty you can sometimes get a text message out. I always carry a snack and H20. I too am single but will let someone know (neighbor, family or one of my daughters) approximately where I am riding and an estimating return time - I will even say "if you don't hear from me by "X" time then I am in trouble." I then make sure inform them of my return. If there is no one around to tell, I have left a note on my dining room table that explains my whereabouts.

I ride conservatively when I am alone. I am a nurse so relatively simple injuries I can handle by tearing a jersey as a tourniquet or to wrap a wound. I have a small set of tools/repair kit with me with a pump and ALWAYS take daylight into consideration.

Don't let being alone stop you!... some of the best stuff I have done was when I was alone, there is obviously no one to compete with besides yourself and I have found that to be liberating. Plus, you can zip along fast because your not chatting as much as you would if you had company.

good luck!