The competition in the field you want to enter is extremely heavy. You're going to have to find some way of differentiating your site from the hundreds of others already in existence selling their own NFL picks. That's a hard thing to do.
Most of the services are dishonest, lie, cheat, and steal clients money. They make up bogus game of year claims and make outrageous claims to make you all this money quick.
I think if you would just be honest and up front and have documented record keeping with realistic expectations and fair pricing you can still make it. Other than that a common misconception is you can throw up a website and start making money. There is so much more that goes into it. You have to be able to win consistently, and you have to know exactly how to market effectively. Also you have to have good customer service and know a lot of the trades to convert clients.