Start with importance of friends in our lives and then move on to 2-3 friends of yours, one from school, one from college and one from work. Then go on to tell him about one of those, may be some incident that you remember or something that had a lot of impact on you.
The basic idea at IELTS speaking is to show them that you can freely converse in English.
Same way for favorite food. You could start with something general about food or by straight away saying that this is my favorite food. I eat it several times a week. You could talk about its taste, preparation, spices, how healthy is it, whether you also know how to cook it, where do you get this food and so on. Ensure that you say 5-6 things at least covering several aspects of food.