Many people find it easier to tell stories which have their roots in their own culture. Make this a starting point. However, if a particular culture holds a great deal of interest for you do not be afraid to explore tales from that culture.
Many storytellers advise starting with Folktales, Myths and Legends which have been passed down through the ages. Their value as a story has been proven by their survival. They usually use language which is naturally spoken and contain patterns which are easy to remember. Literary tales can be too complex or use language more appropriate for reading than telling, and the retelling of personal anecdotes is more skilful that it seems.
Do not try to look at too many stories at one time or you will suffer from mental indigestion. Instead look at just one or two at a time, noting down the ones that touch you enough that you need to tell them. It has been said that ‘a storyteller does not choose the stories, the stories choose the teller,’ and to a great extent this is true. If you are not captured by the story, it will be hard for you to convince your listeners of its worth.