What has grabbed your attention in other flyers that you have seen? That is always a great place to start. Check out the competitions ads, so you don't look too much alike. You may get good ideas about what to do and not do.
I would highly recomend getting your flyer designed by a graphic artist, it is worth the cost, unless you are creative and familiar enough with a desktop publisher to do it yourself. I give a rough idea of layout and copy, and then get a proof. They print out a hardcopy which you can then photocopy or take to a printer.
I like to use a tri-fold flyer with the company name in huge letters, a phone #, and a list of services on the first fold. If the customer doesn't open it up and read inside, they have still seen your company name and services. Send out enough flyers and the name will stick somewhere!
Try to list all of the services that you offer. Go into lots of detail, because if people are going to look at your flyer, they like info.
Hope this helps.
Alan