As Well Getting the email address should be a minimum requirement. It's smart to maybe even get their first name as well. Get their first name, and then you can tailor your correspondence to address them by name, adding a personal touch. Smart marketers don't. They want your email address at a minimum.
Most people feel comfortable giving an email address.
Some feel comfortable giving a first name. A few feel comfortable giving first and last names. But ask for their birth date or yearly income and . . . Ask For Email Address . . . If you have a great tutorial or an ebook you've produced, give it away for free.