"You should take any work that's being offered to you. Never turn anything down, even if it's not the kind of thing you like."
That's the kind of advice that's going to make you not only hate half the stuff you do, but will also get you treated like crap by people.
Don't forget the reasons you want to be freelance in the first place. If you find yourself doing similar work, for similar (often less) pay, working more hours, and working on projects that you don't enjoy, for people you secretly loathe, what's the point?
Don't sell yourself short. While it's fine to take on some projects that might not make you jump up and down with glee so that you can pay the bills and get experience, you can say no to stuff that's wholly unsuitable.
When I started out as a freelance writer, I'd write about anything: make-up, maid cafes, phones, cars, food, you name it. Half of the stuff I wrote about I had no interest in, and it showed through bland, personality-free writing.
Taking on any old job is also unprofessional, because often you won't be the best person for the project, which isn't fair to the client. Don't expect great pay for mediocre work. Do that kind of thing too often, and you really will be fighting for scraps.
When you're working on projects that interest you, your best work will shine through. It's fine to experiment - I ended up much happier sticking to branding, education and language - but don't just take on projects because there's money involved, because you might as well go back and work for a company.