The most important thing for a guitar teacher to do is to convince potential students to choose you as their teacher, and the most cost-effective way to achieve this goal is through the internet. You can try posting some of your understanding of guitar playing and some videos of you playing the guitar, and attempt to attract potential clients from the internet. YouTube and TikTok, as well as building your own WordPress website about guitars, are good starting points. Of course, you can also combine online and offline methods.