I went on a personal credit building rampage a few years ago where I increased all my lines of credit every six months for as long as they would let me. Increasing credit ups scores faster than paying down credit, but it's dangerous if you aren't good with credit in the first place. I eventually got to a place where after requesting a credit limit increase, I'd get a letter back from one card company, referencing another card (and that card's limit) and how I wasn't using that card, or their card, so "no, we aren't going to increase your credit anymore."