Yes you are going the right way. Blog commenting is the best way of gaining solid backlinks. The only thing you have to keep in mind is that your comment should be informative, effective and should be adding values to that blog, so that the blog owner could like to keep your comment on his site for longer.
Alongside you can continue with forum posting to take advantages.

Blog Commenting and Social Bookmarking are the two best way to rank deep links.

Yes, you are right.

Now make links with dofollow, high PR, related pages.

Blog commenting is really very powerful. It helps making huge traffic.

three advantages of blog commenting
direct traffic
get back links
and exposure to your audience

I usually use blog commenting to promote my site and It also gains quality backlinks from related sites forums.