Not only should you describe your expertise, but you should also be able to lead others into your expertise.
Seest thou a man diligent in his business? He shall stand before kings; he shall not stand before mean men - Proverbs 22:29
The difference between good and great in business many times is not sheer ability - it is marketing.
You see the difference between where you are right now in business and where you can be in the future is not so much about ability.
Now, don't get me wrong when it comes to ability. Also, when it comes to the product, the product must be good; the product that you're selling must be revolutionary.
But it's not the product that will get you over the hump.
It's not how much features the product has and how many hours you've put into the product.
What is more important is the marketing of the product and the presentation of your brand as a whole.
Ideally, what you want is to sell people on you and your company before they even have to consider the product for purchase.
Because if you can destroy the objections to the sale before the selling process even begins officially, you can literally have a ticket to money at will.
You can literally write a cheque today and cash it tomorrow if you're able to have a market that has truly embraced your marketing and brand.