Use Bloglines? You're not alone. Have a huge list of feeds in your sidebar, and never read anything because it takes too long? Once again, you're very much not alone. Find keeping up with Bloglines is taking up all of your time? You're one of millions. However, all is not lost. A few simple tricks will make your subscriptions easier to manage and less of a burden.
Bloglines supports folders, into which you can delicately place your various feeds, grouping them together by topic. If when you look at Bloglines all you see is a massive, unmanagable list of feeds, folders should be your first stop. However, when you create your folders, put some thought into how you set them up - once they're set up, changing them later is going to take time, and most people don't want to have to go through the process again. Also, don't name them just "Topic" - name them "01. Topic" instead - give each folder a number at the start and you'll be able to order your folders any way you like, ensuring similar topics are always grouped.
Folders also allow you to spend less time on Bloglines. Keep your personal feeds (yes, including comics) separate from your work ones. You can view the work ones at the office, without being distracted by Dilbert, and keep up to date with friends and pictures of cats when you've got the time. Keep your important folders at the top of your folders list and the task becomes even easier, as you'll avoid having a tempting folder in the middle of the more serious work-related ones.
Website feeds are listed automatically using the name given by the website owner for the feed. For some this may be a problem. For example, I am subscribed to a feed from an Apache blog, and the default name for this is simply "feather". While that might be what their blog is called, it's no use to me - a few months after I've subscribed, I'm going to have no idea what "feather" actually is, and will end up ignoring it. However, I've renamed it "Apache Feather Blog" - far more helpful to me.
Once you've got all of your feeds organised, you may find that Bloglines loads rather slowly. When you've got several hundred subscriptions, that can be a real problem. Fortunately, Bloglines gives you the option to only show feeds with new items - updated feeds. You can enable this under Feed Options in your Bloglines account settings.