he proponents of the "do-follow only" camp have a pretty logical argument backing them up. In terms of SEO value ("link juice", to use the nomenclature) Google should theoretically only count do-follow links. Any link that is no-follow has a direct and clear instruction telling search engines to ignore it. Think of the rel=nofollow tag as one of those detour signs you occasionally see. The street is still there, it's just you're being told to pass by it.
An easy way of getting Do-Follow links is Social Bookmarking, Article Submission on Ezine Articles, do comment on dofollow blogs,do post in a high page rank forums using signature and use quality content and keywords properly.