Make sure to apply following principles to the collected personal data:
- processed lawfully, fairly and in a transparent manner in relation to the data subject, for example, explain to the customer what kind of data you collect;
- collected for specified, explicit and legitimate purposes, for example, you collect the delivery address of your clients to deliver the orders;
- adequate, relevant and limited to what is necessary in relation to the purposes, for example, you may need a full name of the customers to provide a service, but you don't need their birthdates;
- accurate and, where necessary, kept up to date;
- kept in a form which permits identification of data subjects for no longer than is necessary for the purposes for which the personal data are processed, for example, it is useful to keep all the data collected in a special table with established time limits;
- processed in a manner that ensures appropriate security of the personal data, including protection against unauthorized or unlawful processing and against accidental loss.
To sum it up, be transparent about the way your process personal data and use it only for a legitimate purpose.