Save your file with a new filename (like Book v2.docx) and save it in two different places (like jump drive and email). (chrismcmullen.com)
Even if you do use some form of cloud storage, you will most likely want to have a hard copy version backed up on your own jump drives or external hard drives just in case. (smallbusinessesdoitbetter.com)
Flash drive «I always have several jump drives for quick document sharing. (entrepreneur.com)