Nobody can argue that WordPress really simplifies the task of building and maintaining a website, however when you deal with clients and eventually have to hand control of the site too them WP simple doesn’t seem to be simple enough… they always find a way to mess things up.
There are a couple of precautions you can take in order to avoid your clients breaking stuff, from giving them a non-admin user for their everyday tasks to disabling update notices (they will click that button without asking and thing will break, if not the first time, eventually).
But what can be really effective is simply limiting their access to certain sections of the admin. That’s when WP Admin Menu Manager comes in very handy, as it allows you to configure the admin menu on a per user or per role basis. This way you can create different users and make sure that whoever is in charge of community management doesn’t have access to anything other than comments, whoever is in charge of content creation only has access to posts, etc.
There are certainly a number of ways to achieve this, but WP Admin Menu Manager is a simple visual solution, with nice graphics and an intuitive drag and drop interface.