You got to decide what is it you're selling. And you really have two main choices. You can sell services. Or you can sell products. If you are a portrait artist, you're selling your service of painting, but you're selling the final product people get to keep a painting. If you are a massage therapist or a yoga instructor, you're selling a service.
If you devise software, again, it could be a hybrid of the two you're working on their website or you're creating hourly billables of services, but there may be a final deliverable product as well. It often goes together. My advice for most freelancers, most of the time, figure out what professional service you have that is most valuable and sell that service. Now I sell books and online courses like This and in the past, I've sold DVDs and cassette tapes and software prices, a lot of different services. But far and away what I sell in my own business is a day long service of a public speaking training or a media training. So figure out what it is you're going to sell my advice in most cases, it's easier to sell a service than it is a product