Most people try using search engine optimization techniques, which has become so specialized and quite frankly time consuming that most people can't approach page one of listings in spite of months of hard work. Pay Per Click is too expensive, as prices for some keywords approaching or surpassing the $50 per click range. It is certainly not uncommon for a $1 per click.
These list building techniques certainly do work if you have the deep pockets to stay with it in the long term. However, if you have shallow pockets, or you do not want to spend much money on advertising, because you are just starting out, there are several ways of gaining a competitive edge that will cost you nothing.
Take Craig's List for example. They now get over 12 Billion hits per month placing them in the mid single digits of most viewed websites in the world. The cost of advertising on Craig's List - $0.
Yahoo Answers is another great place for quality vs. quantity when it comes to time spent. You have an opportunity there to know in advance if the prospect is even interested in your product or service. The competition is generally low or poor quality. If you have just average marketing skills you can do very well building your list in this Free Marketing venue.
Another great place to market for prospects is at Yahoo Groups. This free marketing opportunity lets you search for groups to join and market to by a keyword search. This virtually guarantees that your promotions will be seen by likely prospects.
That's not all! Forums are usually theme specific and open to all as free members. Not only can you post your business opportunity but you can place an ad in your signature for exposure in your comments. You have a golden opportunity to engage in a direct conversation with a prospect.