A lucrative mailing list is not about how big the list is but about how accurate it is in allowing you to communicate with your real market and not with every Tom, Dick or Harriet. Anyone can crate a huge jumble of email addresses and start mailing them, but getting even a 1% positive response will be lucky.
The secret to lucrative list building is to develop a mailing list that focuses on serious potential customers so that you can fine tune and direct your efforts to the market you are targeting. The secret to doing this is to offer the right kind of freebies on your squeeze page to entice the right kind of people to give you their contact details and that means the freebie should be something directly relevant to what you are selling.
Make the page as easy to read and navigate as possible because filling it with ads and links will distract people and they may click on the links before registering their email addresses. Keep the page short and with the minimum of text so that the focus remains on registering for the free download - that is why you have the squeeze page in the first place.
You must have an eyeball catching headline - people spend less than 5 seconds glancing at a web page before deciding if they want to spend time on it and so you need to grab their attention up front which means the heading must be one that relates to what the visitor will get from you. Ensure that the registration process is simple - have too many steps and people will drop out; ask too many questions and they will resent your being intrusive and may wonder about your motives in asking these questions. Make sure that there is a clear statement that people who register can opt out whenever they want - knowing the option of dropping out is there makes the decision to register easier.
After people register you could immediate give them the link to the download, but a better option is to use mailing software to send them an email with the link - this will allow you to confirm that the email address given is a valid one. Do not let talk of huge lists mislead you - lucrative list building is all about having a list of people who are really potential customers and not just people who's addresses you have come across or bought - that is a waste of your time.