Great tips like ensuring use of hyphens, rather than underscores when using permalinks, really make the difference!
☆ Create effective permalinks ☆
Research confirms that while numbers in a post title entice readers to click through to read an article, they don’t factor into the ranking algorithm for your business website. So keep your slugs short — preferably five words or less. If you’re posting content titled “10 Trending Shoe Styles for Summer,” shorten your permalink to “trending-shoe-styles-for-summer.” Remember to use hyphens and not underscore markings since Google considers an underscore as an extension of the word and this can confuse the bots and reduce pagerank.
For more, check out 10 Tips and Tricks for Improving SEO on Your WordPress Website