Mafunk has some good advice there, and it really does start with defining the purpose of the flyer. I think any direct mail piece should be very specific, and it should state a specific benefit to the recipient to encourage them to take action - however you define "action."
If you want them to call you for more information, you have to sell the benefits of picking up the phone and calling you.
If you want them to visit your site, then you need to sell the benefits of visiting your site. But stick to one objective, and don't try to accomplish more than one thing at a time.
Personally, I can't stand "Awareness" type pieces - you know, the mailings that say "We're so and so, the new design company in town. We've been in business for 4 months and we do this and we do that. Here's our phone number blah blah blah..."
It doesn't inspire me to want to contact 'em, yet I see it all the time in print advertising and on websites! Aargh!
A much better approach is to send a mailing that entices the reader to want to visit your site - and offering something to them for free is a great way to attract their attention. How about offering a "Free guide to help your business profit from the internet" or something along those lines? When they visit your site for the free guide, you then request their email address to email it to them - and when you send it make a mention to encourage them to sign up for your free, valuable newsletter (you do have a newsletter, dont you?) If you don't, you should seriously think about it - as it's a great way for you to build credibility with your website visitors and start developing a relationship with them.
At least if you don't make a sale when they first visit your site, you have the opportunity to get to know them better and encourage them to do business with you over time.
Take a look at Seth Godin's excellent book on "Permission Marketing" and also [http://www.givetogetmarketing.com and [url=http://www.themarketingbible.com]http://www.themarketingbible.com](http://www.givetogetmarketing.com) - there is a wealth of info in those three resources that could help you out as they have me.
All the best,