In order to answer the OP, with ratios declining what you need to do is makes shit loads of landers and
split test them.
Run each a/b test for a couple of weeks, work out which elements on the page are pushing conversions. Might be a change of colour, some
copy,
a well written caption, a strong call to action, a joke, making the
JOIN button green. Etc.
Rinse. Repeat.
It's not rocket science. But you do need to come up with interesting ideas for the marketing. If only there was a company to help people do that.