Recently on twitter we found a great plugin called WP-Optimize which is a database cleanup and optimization tool. It allows you to remove post revisions, comments in the spam queue, un-approved comments, and much more with just few clicks. This plugin is a great plugin for Beginners because it does not require you to go to PHPmyAdmin.
This plugin is a one for all for beginners. It takes care of one of the most important security major that is changing your admin username without going into the phpMyAdmin. It lets you control your revision with one click rather than the codes.
Having a smaller database size will help you by loading your site fast. It will also help you when you are trying to backup your database, and it is great when you have limited space on your hosting account.