19. Don’t say: “Can I call or email you anytime?”

Why? Nobody — even freelancers or night-owls — monitors their work email or phone 24/7. Designers have schedules, too (even if they work from home in their pajamas) and often collaborate with multiple clients simultaneously. You may not be able to get a hold of your designer at a moment’s notice, but you should hear back from him during his working hours. If you’re concerned about how easy it will be keep it touch, make sure to ask when those working hours are (and limit your most important messages to that time) as well what his preferred method of communication is.