To be able to keep in touch with my network I store contact details in Google, LinkedIn, WhatsApp contact lists. This is data I store for a long time. For some collaborative projects I work in cloud-based services such as Google Docs and Dropbox. I minimize sharing personal details in files stored here and make sure this data is deleted from the cloud when the project is finished. Please note that in the case of collaborative projects this is not entirely within my control.
If you have any further questions, don't hesitate to contact me.