Comment on other blogs(not spam!), when you comment on blogs surely someone will check your profile based on the quality of comment and eventually visit your blog. This gives you traffic. But if you know the right blogs to comment on who use dofollow you will also increase your SEO work.
Commenting on blogs definitely does help for SEO. As others have said if they are dofollow blogs, you will get some direct SEO benefit. But even if they are nofollow, then you should still do it.
The reason is that if your comments are good the blogger will probably link back to your site as a thank you at some stage. And if he or she doesn't then one of the many bloggers who read your comments while browsing the blog they're on probably will. That's why it's a good idea to comment on high traffic blogs in your niche.