Buy a Harlequin book. In the book, there is usually a form to get two free books from whatever series you are reading. Along with the free books, they will send you an additional two or four books on a trial basis. You can keep them or send them back, but the free books are yours to keep.
Keep the extra books. This will automatically start your subscription to that particular series. Some of the series they have are Presents, Intrigue, American Romance, Harlequin Romance and Blaze.
Stop the subscription at any time. You are under no obligation to buy a certain amount of books. You may discontinue your subscription at any time.
Subscribe to another series. Every month you will receive your four, six or eight books--depending on the series--and they will send you specials. You can ignore them or you can sign up for another series. You can also cancel the series you are receiving and start a different one at any time.
Start a series by visiting the Harlequin website. The link is in the resource section. There are some great deals there on books that would be just a one-time deal or you can subscribe to one of their series. You will notice when you visit that not only can you buy or subscribe to the Harlequin series but other series as well. You will still be able to get the two free books at the website.