A good comment is not saying "Good job! :)" because that dosen't help the blogger at all. A good comment is helpful to someone, so a good comment would be somthing like "Your blog is good but I think you shoul explain this better." or "I don't understand this part.". When you leave a comment make sure you actually finish reading the blog, and use key words from the blog(it makes you sound more professinoal). Also if you leave a good comment the person who you left a comment to just might give one back to you! Lastly make sure you are L.A.R.K!