Why should you use a CMS?
The main reason for using a CMS is to simplify the creation and editing of content. Developers shouldn`t forget that this is the main functionality of a CMS (regardless that content is text, contact forms, user authentication systems or community builders). If they remember this, they will have more time to focus on web optimization, design, usability, security and many other things.
The biggest mistake that you can make: choosing a “geek friendly” CMS
It is imperative for those developers building sites for customers that they remember that not everyone is as tech savvy as they are. Even if you like Joomla, WordPress, Drupal or even Java based CMS-es, you have to remember that someone will have to run the website after your work is done. Even if you customize the CMS, the best option is to pick a simple admin interface (this is not a vote for WordPress).
The second biggest mistake: choosing “the biggest” CMS
Beware of any CMS, whatever its name is, that boasts with its large developer community, with the huge number of people that are using it of the beautiful plugins or widgets that exist right now.
These things are not guarantees that the CMS will be the right thing for your institution or your customer. In 1 month, those developers might fall in love with another CMS and stop offering support to yours; the CMS might fade out and, perhaps, the admin interface is not so user friendly.
What to look for in a CMS?
You need a CMS that can be quickly and easily installed, had an easy to use administration interface and the extensions (plugins, widgets etc.) can offer you great extra functionality through a simple installation process. It would also be helpful to have a simple template manipulation process and a strong community support.
The best CMS-es right now:
WordPress: From blogging platform to CMS, WordPress it is, right now, the most user friendly CMS with a huge developer community.
Joomla: With a huge developer community, but a complex admin interface, Joomla is great for website with multi-instances websites. It allows for great community building websites.
A final advice: never let your IT guy choose the CMS.