How to Promote website through Blog Commenting?

I had a question (This has nothing to do with back links, only promotion of websites):

What is the best way to promote your website through blog commenting (while giving valuable comments)?

OUTSOURCE!...Trust me blog commenting is such a grind for such little results, it's always best to outsource. But make sure when you do, your getting only do-follow blog comments, otherwise your just wasting your time. Alot of SEO companies offer this for very cheap, and they actually post decent comments...Just google do-follow blog commenting service, and you'll find some good ones