There are a lot of ways to gain more back links for your blog, however, in my search of more back links, I have learned that these 5 ways are the most effective.
1. Submit your blog to Free Web Directory
There are thousands free web directory in the web, submit your blog in each of them and surely your PR will increase.
2. Link your Blog to your Signature
You have to participate in forums. I am sure you can find more interesting forums related to your blog or forums regarding your interest or profession. Add your blog's link to your signature and try to reply on forum discussions.
3. Ask Blogger for a Reciprocal Link (Exchange Links)
One essential element in blogging is the reciprocal link or perhaps what bloggers mostly call them as blogger friends. Contact them in any way you can and ask them to exchange links with you.
4.Submit your post to social bookmarking sites
I believe that you know what are these social bookmarking sites. Submit your post to the popular ones only like Delicious, Google Bookmarks, Propeller, Technorati, and many more.
I believe there are still more effective ways to gain backlink for your blog. If you want to make it quick and easier, then you should spend your dollars to paid services.