Start talking to service workers and such. As an introvert, it's probably easy for you to stay positive during conversations. Say little things like "selam, endet nachu? Alen egziabher yimesgen. Enten enten fellige new. Aha Eshi ameseginalehu. Selam walu. Ciao." with much courtesy. I know, it's weird and sounds like a character on some cliche ad would say. But it's a very nice practice and you get more comfortable talking to strangers directly. It also makes you more likeable.