Using misleading keywords is not recommended, and is risky. Register pages for all the individual search engines, and keep on top of changes. Every search engine has a different method, and they change frequently. Be careful not to use those quick one-time services without checking them out first. They do not believe they will find what they need on the first page.
Poor descriptions are one of the reasons people are bypassing search engine links.
One clear sentence or phrase describing who or what you do is valuable and necessary. The hope is that someone will click on your ad and come to your site. The fact is that almost no one is clicking on banner ads any more. This means that less than 1 out of 100 people will actually click on the ad and come to your site. However, placing, trading or buying links is not a good idea without careful consideration.