Avoid telling personal information over the phone or emails
Choose privacy-focused service providers and reputed anti-malware.
Make your online purchase with Paypal or by Credit card if possible as it came with fraud insurance.
Know that it is possible to impersonate any phone number including the shown name. Call back to see if it is real - don't feel bad saying that you will call back if is important info.
Never enter your Credit Card or personal details on an HTTP website — HTTPS has been implemented for encrypting information traveling on a website to prevent other users from reading your datas.