Pick something that you use in a language that you're familiar with. Look for github/jira issues tagged something like: 'good-first-issue', or just interesting

Pick something that you use in a language that you're familiar with. Look for github/jira issues tagged something like: 'good-first-issue', or just interesting issues in general. Honestly you will learn a lot just setting up a project and getting the tests to pass if you haven't done that before.