I know mostly blog commenting site gives you no-follow back links. But Google like you link on relevant blogs sites. I advise you to use mostly wordpress site or BlogSpot site for blog commenting not discuss. Things you should be keep in mind during blog commenting….
- Use only your niche related sites
- Don’t commercial comment
- Try to participate through Q&A
- Use this query to find blogs sites…
- Your keyword “post a comments”-login