What you should try is creating a landing page that is designed to presell people and not just have some content and banners. The purpose of the lander to pre-sell...
In my experience landing pages are not good for email submits and freebies but I am not pretending to be a pro with email submits trust me...so I would like to really here what others have to say on that...
As for a landing page I often use them for offers that payout at least $3 or more. So this wipes out most email submits.
Now I will focus on what the offer is...and try to figure out why my audience want this service.
Then I create 2 or more different landing pages with the sole purpose to presell...
An example of a landing page I have used for example is
http://clicketycoupons.com/
Here is a landing page that can be tested in many different traffic sources and sub niches and the offer is a Coupon toolbar that pays around $4 when someone simply installs it. So instead of doing what every one else does which is to focus on coupons in general you can focus on sub category... coupons for laundry soap, coupons for toilet paper, coupons for baby supplies, you name there is a coupon for it...then design the landing page specific to the offer...
Now depending on the source of traffic and how you target the traffic you will send them to the appropriate landing page. For example, lets say you buy a banner on a forum related to pregnancy - then your banner should be related to "baby supplies coupons" and your landing page needs to also say "install this toolbar for unlimited coupons for baby supplies!!" or something of that nature...
So recap....
Choose the offer
Understand your target audiences
Look for viable traffic sources
Create a few landing pages based on the offer and sub-categories (of different angles)
Target the traffic to the landing page and angle you are taking
List the benefits on your landing page
STRONG CALL TO ACTION ON THE LANDER
TEST, TEST, TEST
