For example, I type superuser.com in the browser bar of Firefox, but it automatically goes to the HTTP site. I want the HTTPS site by default.
Firefox – How to get Firefox to prefer HTTPS over HTTP
firefoxhttps
Related Solutions
NoScript for firefox solves this problem:
http://noscript.net/faq#qa6_1 (last three lines of the paragraph)
Details here: http://hackademix.net/2008/09/10/noscript-vs-insecure-cookies/
It was removed in Firefox 4 - the intention now is that the site's security information is presented in the Site Identify button. You can add a similar concept of a padlock back to the Site Identity button with the Padlock addon.
Best Answer
Another alternative is HTTPS Everywhere. It's available for Firefox, Chrome and Safari.
Since it is developed from the collaboration between EFF and the TOR project, I tend to believe this plugin more.
It's also open source and available under GPLv3 license.