Are you being swamped with RSS content? Me too, and while waiting for mainstream feed readers to include built-in filtering support I am going to tell you how I deal with it. I am using 2 approaches for streamlining my Google Reader experience: one for removing the irrelevant posts from a feed, and another for prioritizing my subscriptions.
Removing uninteresting posts
When subscribing to a feed, your best option will be to find one that only contains the posts you are interested in. This blog, for example, provides individual feeds for each tag or label. If you are only interested to read new posts about .NET you should subscribe to http://jonasmartinsson.blogspot.com/feeds/posts/default/-/.NET.
You are not always lucky enough to have your favorite web sites return a relevantly filtered feed for you. But don't despair, the solution is just a click away: FeedRinse provides a free RSS filtering service where you can set up rules based on titles and content. I have been using their service for many months and it has been working flawlessly.
Prioritizing your feeds
One of the many great features in Google Reader is the option to tag feeds (or folders, as Google calls them). This allows you assign a feed to more than one folder, which a traditional RSS aggregator doesn't let you do. I am using this to tag my favorite feeds with "-a-list", "-b-list", and "-c-list" along with their normal categories. I put feeds which I don't want to miss in the "-a-list", while less critical feeds will get the b or c rating. Feeds which I only read occasionally will not get any of these tags.
By prefixing the folders with a dash, I am making sure that they are showing up at the top of my Google Reader subscription list, which is sorted alphabetically. By reading my subscribed feeds in top to bottom order I can feel confident in having read the most relevant posts, in case I won't have the time to browse all new posts - a luxury I seldom have.