Seeking help with postcard mailers

I’m planning on sending out postcard mailers to market my copywriting business, and I’d love to get the Biznik community’s help with some tactical questions I have. Even if you’re not a copywriter, if you’ve used postcards I welcome your ideas.

Here are my questions:

--I know there are directories of graphic design firms, marketing agencies, PR firms, and corporate communications officers—my target audiences—such as O’Dwyer’s and the Standard Directory of Advertisers. But these are pricey to order online, and the paper versions cannot be removed from the library. Can you recommend other ways I can get electronic versions of lists for these industries? Or should I plan on photocopying pages from the directories at the library and then manually typing specific firms into my own database? That sounds like a really time-consuming process.

--What do you think really catches the eye when it comes to a business postcard?

--In your opinion, will a 5x7-size postcard get enough attention to justify the fact that postage costs are about twice as high as for the 4x6 size?

--Is hand writing the addresses more effective than doing mailing labels?

--Any other tips you can share?

Thanks for whatever comments you have!

Robert Lowry