I wouldn't say to *never* do things for exposure only - with blogging collabs, for example (though I've done v. few of those, the ones I have done were lots of fun,) you both/all get more-or-less the same benefit depending on what you've agreed before hand. I think the key is only agreeing to the ones you actually wanna do.

I don't do blog tours though - that's where you promote a book for an author or publishing company, and agree to post it to a deadline and do a book cover reveal, or a feature spotlight, or an interview, or whatever. They're a lot of work, I don't even enjoy reading them, let alone writing them, and they are notorious for Authors/Publishers Behaving Badly; sometimes you get a review copy of the book out of it, and if you're lucky it's a physical copy, not a digital copy which self-destructs after a set amount of time.

As far as music goes... unless it's like a charity thing or like, a community thing which you've volunteered for and know that no-one gets paid for, then I'd say you def. need to be paid. You're literally performing - and if it's at a top level, then not being paid is just taking advantage of people tbh. If you wanted to work for free/pennies, you could post stuff on your own YouTube channel - and that would probs be a lot less stress! :)