Some pretty simple tips to make sure you are not an 'easy-target'.
Email is not a secure form of communication; never share sensitive information such as credit card information; documents with your signature on it. Always protect your computers from viruses, worms, Trojans and unwanted SPAM / phishing scams etc.
Register your own domain name. This will also protect you if you ever need to change your Internet Service Provider as you will always be able to keep your Domain Name Email Address (i.e. firstname.lastname@example.org).
Make sure you set up your email address properly so that when you send email addresses the receiver sees email@example.com. This will provide a professional image when potential and regular customers see your email (believe me I know a lot of businesses that don't do this even though they own their Domain Name). You can normally set this up in the Tools > Accounts menu of your email browser.
Here are 10 tips to help you with managing your emails, aliases, email signatures and SPAM.