Clearly identifying your RSS feed with Feed Icons is important. The standard for a web feed icon is this:

The color is irrelevant, although orange is mostly used. I like the blue version, personally. Regardless, using this feed icon helps create a web standard that anyone can recognize.

To further make subscribing easy, you can use this generator for RSS buttons such as this one:

Tags: feed icons, rss icons, rss feed icons, blog, blogging, blogs, rss, marketing