When your selling soft goods you can use the same techniques used for hard goods. The only thing is that you should push is an instant purchase (subscription) type of method. This would be like a credit card or my favorite Pay Pal.
When your selling a soft good, you have your customer already locked in. They are ready to view your content or get your information NOW. People by general nature are very impulse orientated. Even in standard stores impulse sales make up for a greater sale and EVERYONE falls for it. Just ask yourself how many times you went into a store after a particular item and walked out with other things. The other things you bought on an impulse.
Soft goods are by nature very much impulse sales. People have found your site and now they want to buy, not tomorrow, not in an hour, they want to Buy NOW and you have to be able to take advantage of that. The only real way to accomplish the sale is to have some sort of method that they can pay and get access right now. This means using and instant payment method be involved, along with instant access to the product.
Pay Pal is one of the best ways to do this. People can click the link fill in their info and instantly have access to the content through what Pay Pal uses as a re-direct after the purchase back to your site. This way you get the sale right away and they get what their impulse at the moment says they want.
Selling soft goods and getting paid for them is just as easy as selling hard goods.
Sparky