Nowadays,
Here are some great methods for making your comments stand for long and bring you the value that you are looking for :
1. Read and understand the entire post
There are literally million of comments on the web with only « great post, thanks » and so on, and almost 99% of those comments belong to people not even reading the post. Read the post, understand it and contribute with a good comment.
2. Related post
If you are for example in the cosmetics niche, commenting on an iPhone blog post will definitely not bring you any visitor while they are not interested in your website. However finding a post like « creams that make you skin brighter » and coming with some other examples or alike ones might bring you some extra-traffic solely from the fact that you know what you’re talking about and you also have a website related to what the post is about.
3. Do not only use keywords as names
There are webmasters that also accept keywords as names and webmasters that don’t, most ones come from the second category. By using the full name when commenting you get A. more trust from the blogger and B. much higher approval rate.
4. Come back for more
No, it is not about more comments a.k.a more links but coming back to see whether you got a reply or a question you might answer. This is all about building a trusty relationship not only with the blog owner but also with its visitors. A best thing to do is to subscribe to future comments on that particular post you’ve comment, that’s how you’ll not miss any opportunity to show your expertise further.
5. Less links, better value
Commenting on hardly-spammed blogs will get you nowhere for 2 reasons : first, the link juice on that page is distributed to all outbound links and second, when there are over let’s say 50 links on a page the possibility of getting at least 1 visitor through your link tends to hit the 0 margins, so better stay away from heavily commented blogs.