I have had pretty good luck as of late with long tails. Once I learned how to use them it helped because I get less traffic (clicks to pay for) but I get much more targeted traffic and it has increased my sales.
I actually joined a internet marketing site that teaches you how to make a career out of IM. I got tired of the crappy e-books and a friend suggested it to me. I learned a ton about "long tails" and improving my cmapaigns in the 8-week beginners course.
Check it out if you need help with PPC campaigns.
WA Internet Marketing University