A lot of marketing methods are already suggested by SFI at: "http://php.sfimg.com/Resources/Marketing/StandardSponsoringMethods", from where you can choose the one which suits you the best.
The best is decided by you, if you are internet expert then go for internet marketing or else warm marketing. It can also be done with the x-cards and flyers provided by SFI.
Use the method you think best suits you and devote yourself completely to it, you are sure to get RESULTS.