Similarity in Interest
There is rarely a point to leave a comment on blogs that have nothing at all to do with the main theme of your blog. A direct connection is unnecessary but preferable. If you are, for instance, maintaining a vitamin supplements, you dont always have to restrict your comments on blogs that tackle the very same topics. You can also visit a beauty blog, for instance, and post comments regarding the benefits that vitamin supplements offer with regard to ones physical appearance.
A quick way to determine the nature of any blog is by checking out its blog description. If there is none, just browse through its content and see if youre targeting the same keywords.
Popularity
Likewise, its senseless to leave comments on little-known blogs. With such a small readership base, you wont be able to justify the amount of time and effort it could take you to post the best comments. If youre going to use comments to promote your blog, its better to post them at blogs that are equally popular or more so than yours.
You can use the blogs page rankings to determine the popularity rating of other blogs and compare it with yours.
Likelihood of Reciprocity
Naturally, its best to concentrate your efforts on blogs whose owners are likely to reciprocate your action. Whether or not youre the first to make contact, as long as the other party benefited from the comment you posted then its only good business for them to reciprocate.
To determine the chances of having comments left on your blog and link exchanges, try reading the previous entries in other blogs. Follow the links of those who posted comments on their blogs and see if the favor was returned. You know what to do next.
Similarity in Target Market
Blogs need not have the same interest in order to benefit from comment exchange. With careful planning, traffic can be generated for two different blogs with just a couple of comments posted on each others entries.
A dance blog and a food blog may not have anything in common at first glance, but if you look more closely, youll realize that both of them may target the same age group. Two different blogs may also have target the same geographical area.
If you can find a major connection between both your target markets, beneficial comment exchange is very much possible but only with careful planning. First, youll need to think of a topic that could link your interests together. Just concentrate on your target market, and youre sure to find one.
If we go back to the food and dance blog example and assume that both are targeting teenagers, articles that could require the blog owners to exchange comments would be about the best food for dancers during competition and the best dance workouts for those on a diet.
Of course, its not bad at all to leave a comment on someone elses blog just because you want to. If you have the time and the inclination then go ahead! There may be no way for you to benefit from such an action now but this small act of generosity and goodwill could turn out good for you in the long run.