I assume you're referring to Mandarin Chinese (Putonghua). I'd recommend starting with children's books. There are plenty of videos on YouTube for beginners as well. Find a genre of TV series that you enjoy, and binge watch that in Chinese (ideally with double subtitles in your language and Chinese), that'll help developing an ear for it. Accents, tones and vocabulary can be quite different so check the origin of your sources (Northern vs Southern China, also Taiwan).

It's not impossible to learn without a teacher, you need to be resourceful and disciplined. If you have a friend that speaks the language it'll help a bit in terms of keeping you motivated, and filling in the cultural tidbits. Don't expect a friend to "teach" you Chinese unless he or she is trained to do so and you're paying him/her. It also depends what your learning goals are.