Always ensure the authenticity of Website URLs. Never visit any untrusted sites or Web Apps.
Keep habit of checking emails spellings and Subject before opening them. And don't click on any untrusted links or attachments.
Always log out from any of web-services, once you are done with respective session. If possible don't login within any untrusted network or devices.
Choose as lengthy passwords as possible and always use combination of digits & special characters within your password.
Alwayse make your transactions on secure networks & applications. Also be aware of Phishing URLs & links.