Consider a scenario where you are starting a new business, and are fairly novice in the area. Will you build competency first, or get business first? Is it not the chicken and egg situation that all entrepreneurs go through? What is the solution then?
I am of the opinion that one must first build competency, whatever be the costs. You may have to offer a service free to the customer to gain his confidence and make a mark in the market. There is no other way you can offset the apprehension in the prospective customer's mind. Consider this as the cost of entry into the business or a one time marketing cost. Ones you have put some experience behind you, made some name for yourself, it will be fairly easy to demonstrate capability in further proposals as you will have credentials to show off.
However, if you chose to win a deal first and learn at the expense of your customer, I look at that as a big risk. Yes, the risk does have commensurate rewards, but not worthwhile I think. The very fundamental of your relationship with the customer is a lie. Failure to deliver can cause irreversible damage. But this approach gets your cash counters ringing at a time when you are really in a need for it. A couple of lies, a good deal now & then, and you have all the time in the world to gain customer's confidence. Building a competency can take forever and you also run the risk of being taken for granted by the market.
What is the right approach then? A consultant would definitely start the answer with 'depends'. What do you think?