Yes, yes, yes, and yes.... Do what Lola says! None of those things are specific to solo travelers, mind you. Any and all visitors are subject to those four specific things. And like Lola says, if you take care of your items, you won't have any problems.
I've never had anything stolen, but I have had something returned! My iPod fell out of my pocket in a taxi and the driver came back to give it to me. Not exactly an anti-theft story, but the majority of people you will meet are warm, inviting, and whpant to make sure you are having a good time.