Feel free to consider this an official recommendation.
If you author a blog or a web site to which you'd like more subscribers and you don't yet know about Daniel Scocco's site over DailyBlogTips.com, then you'll want to check out his post about 50 Simple Ways to Gain RSS Subscribers.
Afterwards, find his rss feed on the site and subscribe. There's some useful information there--with more than a few things I just added to my to do list for this weekend. :(
My personal favorites from the list:
#5. Write a post asking for people to subscribe. (And also to either include a "how to" in the post or link to a special "subscribe" or "welcome" page on your site that shows visitors how to subscribe.)
#25. Have a special "subscribe" page with all the infor and links there. (Something you'll notice I'm lacking. What do you think, will it help?)
#26. Create a landing page on your blog.
#30. Offer a full feed. (I like this one especially because it's a pet peeve of mine for blogs that I subscribe to. You'll notice I use a full feed in mine. What?! "You wouldn't know?" Then that would mean you're not subscribed!) ;-)
#47. Use testimonials on your "Subscribe" page. (Never thought of this one before. I've used it on other--sales-type--pages. But never considered it for my blog. 'Makes sense.)