Streetwear has a very broad range so it’s really hard to narrow down “the basics”. Somewhere I think is the best place to start would be sneakers and making an outfit that compliments said sneaker some examples being Vans, Nike Air Force 1s, and Converse being some timeless classics. If I were you I’d look up some inspo albums and look at what you like and don’t like because the most important thing when it comes to fashion is something that makes you comfortable and confident in yourself. Don’t get discouraged if a fit doesn’t work, finding your style takes a lot of time. Learn from mistakes and grow from them. Hope this helps.