Guest posting is the best way to build links for seo pusorpe and Forum signature links are pretty useful as well. I think blog commenting is another way to build quality links. But I personally think using target keywords all the time for blog commenting is not a valid process. Blog commenting is about participating in a discussion and providing your point of view according to the post. Unique contents publication and sharing it with social media is the best way to attract your audience. If we could combine all this tactics, it would be good for seo.RegardsSara Fargoons