Gmail is one of the few free email services commonly used for business purposes. While a custom domain looks more professional, adding personal touches to a Gmail address makes it look more professional. For example, adding a signature to your outgoing messages gives them that "business standard" look. Gmail adds your custom signature to messages before you send them, which means it's easy to remove the signature for personal messages sent using the same Gmail account.
Open your preferred Web browser and log in to Gmail. Click the gear icon at the top right of the page to access your settings menu. Click the "Mail settings" option.
Scroll down to the "Signature" section. Start typing your custom signature in the box provided. Use the buttons to add text effects such as bold, or to add a link to a website, blog or other page.
Click the drop-down menu above the box if you have more than one email address and select the email for which you are creating the signature. Scroll down and click "Save Changes" after creating your signature.