Well, I can think of a number of things.

It gets fairly complex - there are a number of factors to consider.

I would remove your "sample pics" from the index page - that first sales position is an important one, and there's no real benefit in distracting any attention from the potential click.

Your first banner is too small, and you neglect the first sales position. Make the first sales position bigger and as attractive as possible.

In general, your banners are too small.

Your first sales position text is neutral "Get instant access to Filthy Uniform Guys now!" - this does and says nothing that attracts a click.

You dont have a second sales position on the index page - you are wasting your surfers page-viewing flow with no benefit to yourself.

You are using a style command to change the colors of your text, which is good - but, you turn the color from a bright color to a dark color (lime to red) which reduces the clicks on the link.

There's a ton more that could be said - I'll leave it there and let others make suggestions too.