Once you've done all of those basic tests, you are ready for a "live" test.

In direct mail, copywriters select a small number of names from their database, mail the letter, and watch the response. That takes time, and it can be expensive. Luckily, on the web, you can do the same thing much cheaper.

It can be done with a bit of PPC, tweaks to your landing page, then more PPC until it all starts working.

(If you want to save money, you could start driving traffic to your site via article marketing instead of PPC.  It takes longer, but it's free).

Now I am not going to go into the specifics of setting up a Pay Per Click campaign, there are a lot of other books and websites out there that will tell you everything you need to know.

But I will tell you to limit your risk by placing daily limits on your spending and carefully monitoring your response and conversion rates.

You should shoot for a conversion rate of about 1% to start. If you are getting less than that, then don't expand your Pay Per Click campaign. That is the absolute minimum you should strive for. (Of course, if you need a higher conversion rate to be profitable, then you should shoot for that. Or change the product you are selling to something more lucrative).

If you are not getting the conversions you expect, you need to tweak your letter. Change the headline. Change the PS. Change the first paragraph. The colors. The layout. The offer itself. Or change the keywords you are using in your PPC campaign.

You might also consider using split testing software to track the impact of various changes in your copy.

Once you reach that profitable conversion rate, then continue testing and refining your copy until you reach 2...3...4% or more.

"Test, test, test" is the mantra of direct response marketing. You need to is to constantly test all components of your offer. You need to have a mechanism for tracking conversions and tying changes in conversion rates to changes in your sales letter. It's the way copywriters make money.

When you finally have a sales letter that converts at a profitable rate, you can increase your PPC spend. Just keep monitoring your performance to ensure that stays profitable.