Many years ago I ordered a manual on starting a sports service from a well-known company that specializes in new business ventures. In the manual one of the key points that was stressed was that as much time as possible should be devoted to marketing, with any remaining time spent trying to actually pick the winners of games. While this is no doubt good business sense, it doesn't seem exactly fair to the paying customer, who is paying money for winning picks.
A number of the larger sports services have employees who are in sales, which means they do anything from answer phone calls from perspective customers to calling former clients or clients of another sports service whose name and number was purchased. Years ago, horror stories were common of sports services calling people continually at home and at work, essentially harassing them until they either purchased the service's selections or changed their phone number. Fortunately, that practice seems to have gone by the wayside, or at least diminished in frequency to a large extent.
The main marketing tool for any sports service, however, is its past record, which just so happens to be the one area where the most blatant occurrences of deception occur. There is the widely told tale of one sports service which placed a large ad in a newspaper boasting of its 7-1 record the previous week. The only problem was that because of advertising deadlines, the sports service had to submit its new ad before the prior weekend's games had even been played.