Your best bet will be to give away something that’s valuable to your target market; for instance, a high-value digital asset on a niche topic. You can give away products (we’ve all seen contests where the prize is a free iPad or gift certificates), however this strategy often leads to entrants who are more interested in the money than in what you have to offer.
Every ESP will give you tools to create an opt-in form for your site. Generally speaking, the less information you ask for (at this initial stage, at least), the better. The more information you ask for, the less likely your prospect is to complete the process. You’ll obviously need to ask for an email address, and I also highly recommended that you ask for a first name so you can personalize your emails. However, asking for any information beyond these two fields can decrease conversion rates significantly without adding much valuable data.
Always remember to customize your messages to blogs in your market and provide them with high quality, unique articles that help their audience and readers. If you do that, you will succeed with guest blogging if you apply it consistently in your business. Every month, you should be posting at least 2-4 guest articles on other sites to see consistent results with this method.

You can use this strategy to your advantage and increase your email list by giving people an incentive in return for their email. The giveaway could be free access to an e-book, a report, a gift hamper, or perhaps a lucky draw where people enter their emails and get a chance to win. A tantalizing offer is all you need for people to comply. For example: