Your free incentive can be virtually any content that has value; audio, video,.pdf file, newsletter, or ecourse. Crafting your own digital content mailing list can take a lot of time, and have substandard results. Try to find a professionally created product that has "give-a-way" rights. Some resale websites create niche content that actually comes with 'give-a-way" rights included.
Otherwise, you will need to have new content specifically created, hopefully at a reasonable price. Next, you're going to need a domain name and hosting account. Try to find a.com domain name that's relevant to your target market. In your mailing list planning you should have discovered some popular keyword phrases, use those phrases to your advantage when choosing your domain name.
Owning a premium.com domain name and reliable hosting account are requirements for virtually any kind of online marketing activity. Autoresponders are the foundation required to start an email campaign, and you must have one to manage mailing list your subscriber list and email broadcasts. I strongly recommend paying a highly qualified autoresponder service to store and manage your list.