How to play a 3v3?

I want to make a ranked team with someone, I dont know who yet, but I want to know how to play 3v3's well. Its not going to be the top jg mid adc supp team comp anymore, so what is it? Are there rotations? What is the order of importance of objectives? Are there build differences? What is laning like? Is jungling a thing, or just something you pick off for extra gold in between rotations?