The majority of my career I've spent in government and higher education. I've trained a wide variety of employees to write, edit, and manage their own content on a CMS. Here are my top 5 tips for managing web content in large organizations.
Tip #1: Writing and editing the content is more important than placing it
In other words, Content Managers should be focusing on editing their content and delivering what visitors to the site need as succinctly and authoritatively as possibly.
Put your best information down in the form of most important to least important and always keep your audience in mind. Let the people running the site worry about where to place it--you're in this game because you're an expert in your field, not theirs.
Tip #2: Use your resources
If you're a Content Manager and you haven't spoken to the Website Administrator or Communications Analyst in charge of the website in months--there's a good chance that your life could be much easier if you did.
There are people in IT, Communications, Marketing, etc. who can help you make your content better--get in contact with them and don't apologize for being needy. The best Content Managers are the actively engaged ones. Feel free to ask for training as well.
Tip #3: Learn some basic HTML and CSS
These days, knowing some basic HTML and CSS can always come in handy. Lynda.com has a variety of excellent courses, but I would suggest in particular the Basics of HTML Syntax on the HTML Essentials course. There's a brief section of videos on HTML and CSS in this course.
I've yet to meet someone who thinks that learning some HTML and CSS was useless in a business setting. If nothing else, you'll have a better vocabulary on hand when speaking to those IT or Design folks.
Tip #4: Collaborate with other Content Managers
You run into problems with content, they run into problems with content--why not meet up and go over your work? I've had people ask me why they should attend my training sessions when I don't go over anything that specifically relates to their current work, and I tell them that if nothing else they can collect from or add to the wisdom of the group.
There are a lot of tips and tricks and you only have so much time--collaborate should never be a dirty word when it comes to content management.
Tip #5: Always give them just the info they need
Nothing less and nothing more.