I think there many general subjects that you can talk about. May be you should talk about the subjects that you are interested in such as: travelling, tourism, valuable things in your life, friends, your idol, technology, a country you would like to visit or which phase in your life is the best and why? You can choose as you like. Firstly, write down all the main points you will talk about. secondly, organise your ideas. finally, you should begin to write a meaningful introduction of your subject.

Find out the person's interests and let them know yours and you both can take it from there.

Try to avoid politics and religion, those lead to debates and fights, sometimes hurt feelings as well, talk about things you like doing, your dog, places you been to, etc