You can make Gmail more secure by enabling https settings. Practically this will results in minor change of URL for Gmail access from (http://mail.google.com) to (https://mail.google.com). Https setting is considered more secure while accessing Gmail from an unsecured internet access like from a public place.
Enable https settings for Gmail
1. Login into Gmail & click settings option at top right.
2. On Settings page, under the General tab scroll down to the bottom and check for “Browser connection” settings.
3. Click and highlight “always use https” and then click on save changes button.
Above will result in more secure Gmail. Please note, enabling this setting may cause error while using Google toolbar, Gmail on mobile and Gmail notifier utility. Incase you do not use either of them, keep https enabled for more secure Gmail.