I've been having troubles on drawing clothing folds when I draw people... I'm looking for tips that can maybe help! ^^

Everything comes naturally if you just play with it. No matter what foldings and wrinkles will look ugly if you think about it so just play with your drawing.

There's a couple of tutorials on deviantart, you should search for that, also you can try to use google. If you're planning manga, you can try How To Draw Manga, it's explained pretty straight forward. Other than that, you can look at models, reference pictures or yourself in the mirror, and kind of decipher how clothing works, how physics pull on clothing, and how different materials fold differently depending on how stiff and how thick they are.

One of the things that helps me is drawing kind of slug-like shapes for where cloth could bunch up, then erasing the part where it separates itself from the cloth so that it just becomes a fold. If that makes sense.