In a recent issue of my e-zine, I quoted an article from Catalog Success that advised repeating keywords on your site as often as possible, and in multiple places, so search engine “spiders” can find them.

Pretty standard advice. But as soon as he read my issue, copywriter Nick Usborne e-mailed me to let me know what he thought of the suggestion.

“This is the worst possible advice you can give to anyone about optimizing their site for the search engines,” says Nick.

“It’s an element of what is referred to as ‘keyword stuffing’ and is either ignored by the search engine algorithms or, in bad cases, your page and site will be penalized. Worse still, it results in pages that read very strangely to human visitors.”

What about you? Do you try to get your keywords into your Web copy frequently, as Catalog Success advises? Or, like Nick, do you use keywords sparingly?

And more important, have you measured results to see which approach works best?

The subject line “Free Direct Mail Encyclopedia” outpulled “Boost Sales, Increase Profits, and Expand Market Awareness” by 25%.

Three lessons we can learn from this:

1. Just changing the subject line can dramatically increase e-mail response rates.

2. You never know which subject line or headline is the winner until you test it. (The reasons some of you gave for why A would win seemed to me equally as valid and strong as the reasons others gave for B.)

3. The increase in response from the pulling power of “free” more than outweighs any decline in response that may occur from “free” triggering spam filters.

To download your free bonus prize – my $29 report on improving online marketing results — go to www.bly.com and click on Reports.

By the way, this is a classic example of A/B split testing: test two approaches, and see which works best.

Don’t debate the merits of copy by arguing around a conference table. Test it and learn definitively which headline works best.

This is the basic philosophy that separates direct marketing from general advertising – and by the way, it’s completely in keeping with the Cluetrain and blogging philosophies of marketing as conversation:

Don’t tell the market what you think sells. The market will tell YOU what they will buy.

P.S. If you guessed B instead of A, don’t feel bad. I often guess wrong on these challenges myself … which is why I encourage clients to test more than one approach.

Edith Roman Associates, a mailing list broker, uses e-mail marketing to promote their services.

In a recent e-mail offering free list recommendations and a free catalog of mailing lists, they split test two subject lines:

A. Free Direct Mail Encyclopedia.

B. Boost Sales, Increase Profits, and Expand Market Awareness.

Which do you think was the winner — and why?

Choose correctly, and you win a FREE special report on how to improve online marketing results (list price: $29).

(I’ll tell you how to get your free prize when I announce the correct answer.)