I have a slightly different background to many hear so can offer some didferent advice.
Before IT I used to be a commercial printer and over 10 years, knew what works and what doesn't in the world of "physcial" advertising (flyers, stckers, news ads etc).
Rule one.
Keep it simple:
You need to grab attention in less than 2 seconds. If you add has lots of fussy text, too many colours, people won't bother.
Rule two:
Avoid "comicy" pictures
They look like you are a joke. By this a picture of a broken pc is ok. A pc with a silly hat and sunglasses is not!
Rule Three:
Stand out:
If everyone has used Time New Roman on a page, choose a different font.
Rule Four:
Make the following stand out:
Company Name, contact details and "hook line". A hook line is the "Forget the rest, we're the best" sort of thing.
Finally and possibly most importantly, know your market.
Make sure you advertise in suitable publications, no good advertising in a paper 20 miles from where you live.
Lastly remember, YOU are your best add. Get Shirt's made up with company name on it (and web address), advertising on your CLEAN car, smile, be helpful. It takes months to get a good reputation, but seconds to lose it!
Stu..
Only the truly stupid believe they know everything.
Stu.. 2004