There are some simple things to do to your website in order to generate leads. The ones listed here are some elementary to-dos you need to have in order to get those clients.
Place the mailing list sign-up prominently on the website. Some articles can only be accessed once you have signed up. Make sure that you specifically mention that newsletter subscribers will be informed of special offers and discounts.
In some cases, from e.g., a group-buying coupon site like groupon, the newsletter can be as a call to action pop-up, which appears when the user is logging on to the site for the first time. This can be very annoying and may prompt users to not proceed so do this with discretion.