You've finally decided that it's a good idea, in fact a great idea, to backup that WordPress blog. Now if anything goes wrong you have a copy somewhere at least you can put somewhere else. What features should you look for in a WordPress backup plugin? I've seen many plugins that overload you with features. Tell you it'll backup to S3, that it will backup to Rackspace, they add all sorts of fancy features. At the end of the day do you need all that fanciness or do you just need a backup plugin that simply works?
That's why I'm going to tell you, if you're looking for a backup plugin, find one that is easy to use, that can actually restore and it can also clone your site somewhere else. What's the point in having the best backup plugin in the world if you can not use it, if you do not know what to do? That's why if you can not find a backup plugin where you can just click on one button then it's useless to you. Find one and when you're looking for backup plugins look for those show screen shots or videos of the plugin in action. Look at do you have to go through a ten step process, do you have to confirm every step of the way, or can you click on one button and now your WordPress blog is safely backed up.
The reason I say this is because you're not going to just make one backup of your site. You should ideally make a backup of your site at least once a month, if not several times a month, and it should not be a chore. It should be something where you go in, you click a button and now you have a copy. Make sure your backup plugin is easy to use.
Next, make sure that your backup can actually restore. It sounds silly for me to say that your backup plugin should also restore. But you'd be surprised at how many WordPress plugins simply do not work or are out of date. What you should do is install a backup plugin and immediately take a backup. Then go and install a new blog and see if you can restore that same blog somewhere else. You've been surprised at how many backup plugins will not restore. You may be diligently and obediently backing up your site over and over and over every month but if something goes wrong you're in the same situation as if you had not made a backup. The backup did not complete successfully.
This brings me to my final point that your backup plugin should also have the ability to clone your site somewhere else. What's the difference between restoring and cloning? Cloning means that you can backup your site on one location and go to a different website or a different folder and put your site in that new place. All the links, all the information, everything will work just fine. Why is cloning so important? Because if you want to restore a site you might want to restore it in a different location first just to make sure you do not destroy your original backup, your original site. Once you can clone sites it means that if you have your site set up exactly the way you want it you can customize your theme, plugins, settings, memberships, all that stuff. Back it up and restore it or cone it in a new location and now you have saved tons of time for yourself.