is there a sensible way to make a slogan?

what's the business? helps a lot. the process that's worked for me: write down what customers actually say when they recommend you (reviews are gold for this), then write 30 bad slogans fast without judging. the good one is usually a rewrite of one of the bad ones. keep it short enough to say in one breath and read it out loud, if you stumble so will everyone else. before you print anything, run a quick trademark search in your country. cheap check, expensive mistake.