This must take precedence over your tracking their visits and buying habits, and all the other back door things you can do to them, that you would never do up front and in plain view. And you thought you were done when you got your web site up. You might be very happy about your site and its contents, but somewhere in all the protective coding you applied to it, you might have crossed the line with your potential customers, which could negate all the good hard work you put into building your site. Palindrin is essentially a violation of the person of the customer, in the customer's estimation, and it will undo all the good you put into your web site. It might be something as small as having to give their address and phone number on line.
Most web sites ask for much more than that.
The customer is required to register on line before they can see what they came to that site to see. There are hundreds of other examples of this, but all of it is completely unnecessary. Really, all you need to have contact with a customer or visitor to your site is their name and email address. With just these two bits of information you can do all you need to do in doing business with people. Even if you are selling things on the web, having them sign in with their name and email, perhaps to win something, will give you exactly what you need to make them a customer.