Let me tell you something today "Sales is Persuasion and everyone is part of it". A lot of people will tell you that they have never been a part of sales of know anything about sales because they aren't called salesmen or any other name associated with sales but that is not true. We are all into sales either we agree to it or not and it is as simple as convincing someone to agree with you on something.
Going for an interview and telling your prospective employer the reason why they should employ you over others is just selling yourself to your employer and that is sales. Selling does not often require money, it is about persuading people to do what you want from them. It is about getting them to prefer you over another on a parallel level. You are either selling a good, service, personality, idea, and conspiracy, you can literarily sell anything.
Sales is a good thing, forget what you might have heard about salespeople. You only buy what is good for you, so by all means, a sales person is doing a great job as they are only selling the right stuff to the right people. No real salesman is dumb because they persuade you to buy and every sales man who treat a sale as a number is surely going to fail because you cannot persuade numbers but you can persuade people.
With sales, all you have to do is familiarize yourself with the buyer of the product, service, idea or conspiracy. You do not have to prove how good you are to your client that you are good, just get to know them so you can be able to sell to them with no stress. You only decide to pitch your sales when you are to meet with a board formally but then try to be free with them.