At the start, Mrs Fields spent months giving away samples of her cookies in malls to attract people into her shop to buy more! She came up with a great recipe, made her product and then gave samples away for the sole purpose of making sales and making people happy.
Same with you songwriters. You come up with a great song, make a demo/record, give it to other artists or market it for yourself for the sole purpose of making sales and making people happy.
Making the product can be challenging. I will say it right now up front: if you can produce your own demos then you are way ahead of the game. You can realize your track, sound, feeling as you are creating the song. The other option - just as valid, but more challenging - is finding someone to do it for you.
I recently interviewed David Hodges and one of the things I am so impressed with is his ability to work in so many different genres. He understands how to build the appropriate container for the stories he is telling in a way that sensitive to the voice that is going to deliver it.
The demo is VERY important so if you need to hire someone to do it, then find someone who loves what they do, is a multi-instrumentalist, and is easy to talk to.
How you present your songs to get you to the next step in your career is crucial and before you can hire someone to do the job for you, you have to understand the job yourself.
Take control. Get educated. Know what you want for your song and how to communicate it.