Besides phone calls and email, there are a few clients with whom I text message. I try not to make the texts too sloppy, as I have to still be professional despite the medium.
One thing I do is double-check all texts before I send them. Here are some funny examples of the autocorrect feature messing up some text messages (warning, NSFW). I would probably die of embarrassment if these happened to me, especially during a communication with a client!
http://damnyouautocorrect.com/10484/the-top-15-most-popular-dyac-texts-of-all-time/