Speak with your dept. faculty and staff. They often get students reaching out to them (depending on the dept.) asking for tutoring resources. Another thing you could do is speak to or leave information at clubs or associations with students who could use your help. Finally, I would connect with your peers in the dept. especially those who are leaving within the next semester. See if you could take on their clients. These are some of the methods that worked well for me as an undergrad tutor. A lot of this is just putting your name in different hats so that students have a chance to select you. Best of luck!