Well first, you can ask if people in your target market would like to sign up for your newsletter.  It's free. 

They think, why not.  I can unsubscribe anytime anyway. 

Then you could ask, would you like to get this nifty, awesome product that I'm selling?  It's free for a limited amount of time. 

They think,...

Your precious little daughter comes to you at five in the afternoon and says, "Can I sleep over at Suzy's?"  You think about it, and it's not a good idea.  It is, after all, a school night.  So, no, you tell her.

Then with her big puppy eyes, she says, "Well, can I just go over there to do homework with her?"  You think, why not?  I don't want to seem like a cold-hearted mom.

...

It's called the "Foot-in-the-Door" technique.  Ever heard of it?

The basic premise is, if you make a series of small requests and get a 'yes' for them, then mostly likely, you can ask for something big and you'll get a 'yes.'

It's like getting your foot-in-the door.  You'll eventually be able to get your whole body inside, if your foot is already in....