Many good musicians are afraid to perform solo.. I have heard countless times, "I could never do what you do." I then ask them why, and believe it or not, their biggest fear is that they feel alone!! And that they are afraid that people will not like them.
I found out early on, one of the key points in performing solo is to listen to what the people want. By that I mean, their requests. I make a point of writing down requests if I do not know them, and then I will learn the song if possible, so that the next time I perform there, I will be able to play that song for them.. Right now, my entire 4 hour show is made up entirely of all requests.. Meaning every song that I do right now was a request at some point.
I also perform songs from my albums, but right now, cover songs are what pay the bills.
The second most important thing, is good equipment. If you are doing this alone, you need equipment that you know will not fail. Yes, it can be expensive, but, in the long run, it is well worth it! You need a decent guitar and PA.
The third thing I tell people, is just be your self! You are who you are, embrace it. Yes, you will make mistakes, but, when you do, laugh them off..
Have fun with the crowd. The people are what make you, embrace them, they want to be entertained, so have fun, if they see you are having fun, they will have fun.. But remember to be kind and respectful!! Make eye contact as well!!!
These are just some starting points.. Little things that will help you to be successful!