In very first stage of building backlinks it is necessary that you create some .edu and .gov backlinks.
The easiest way to do so is by blog commenting, guest book sign or profile creation on some forums.
You should do this before you are going top create any other backlinks, this will give you kick start of credibility in googles eyes. After you have managed to get 50-100 .edu and .gov backlinks you can focus to build other type of backlinks as well, but not to aggressive.