Typically the amount of data you want get on a sales lead is inversely proportional to the number of leads you can generate. A potential customer does not like to fill-up long forms, even if you give incentives. Therefore the big question is on how to make this inverse equation "less inverse" for lead generation. Assuming other things being equal (like the kind of incentives, gifts etc.., which you are providing..), here are some tricks you can apply:

Some tricks are:

• Just get the basic information from a customer (name, email ID, telephone number..) and follow-up later.
• Ask for customer's visiting card and fill-up the form yourself.
• Use alternative methods- For example you can take a person's telephone number and get his address from telephone book.
• Ask yourself the reason and purpose for asking an information. Most of the lead generation asks for date of birth, whereas, it may not be required in most of the cases.
• Instead of asking open ended questions ask objective questions. For example instead of asking customers annual income, given him 4-5 income ranges to select from.
• Provide both the options to people. Some customers find it faster and convenient to fill-up their information, and some customers like to speak it out.