An AdWords headline can only consist of 25 characters. That's 82% shorter than the maximum length of a Twitter message.

The headline also happens to be the most important line of your ad. If your headline doesn't grab searchers' attention as they quickly scan a Google search results page, your ad will go unseen. That means you have a very short window of opportunity to make those 25 characters count.

Here are nine guidelines to writing headlines that will give your ads the highest probability of being clicked on.

1. Don't use your company's name.

This is a big one that I see a lot of small businesses get wrong. Unless your company is a household name like Amazon, Walmart or Coca Cola, don't waste your precious headline space by announcing the name of your company.

The only people who will recognize your company name and click on your ad are those who are already aware of your business and are probably already a lead or, even worse, a current customer themselves.

And for those who have never heard of you? They don't care what your company's called. They just want to know if you can solve their problem. By using a headline that doesn't grab their attention, they will probably never get the chance to find out.

2. If you're a local business, mention the location you're serving.

If you're a dermatologist in Nashville, Tennessee, put "Nashville" in your headline. Remember, it's all about grabbing the searcher's attention. You have to make the headline as relevant to them as humanly possible. What better way to do this then to put their location in big blue letters right at the top of your ad?

By the way... if you're doing this make sure you're geotargeting your ads OR all of your keywords include "nashville."

3. Use emotional trigger keywords.

Cheap. Free. Fast. Limited Time. Special. Now. You.

These are all words that evoke emotion in people. Human beings may be complicated, but we have the simplest triggers that get our attention and compel us to take action. Use them to your advantage and your ad is more likely to be clicked on.

4. Include the price of your product or service.

If you're beating most of your competitors when it comes to price, don't be afraid to put it right there in your headline with a shiny dollar sign in front of it. Most other advertisers won't be doing this.

5. Try reverse psychology.

"Don't Buy < x >," "Don't Try < x >." Replace x with your product or service. If you use this technique, in line one of your ad you should lead with something like "Unless you buy from us." This will almost certainly stand out against other ads in your industry (unless your industry is internet marketing).

6. Make an outrageous claim.

"Acne Free In 3 Days." I haven't checked to make sure that's 25 characters or less but you get the point. Make a bold claim, but make sure that your landing page backs it up... Google actually has rules about this. You don't need scientific reports (necessarily), just be sure you have some info on the page that supports your claim.

7. Put it in quotation marks.

"Studies have shown" that human beings' eyes are "drawn to quotation marks. "

"See" what I mean?

8. Use at least part of your keywords in the headline.

If you're bidding on the keyword "gourmet catering," don't just run an ad with a headline that says "Food Delivery." You want to use at least one of the keywords in your headline for two reasons: one, because any words that match the Googler's search term will be displayed in bold (ex. "Fast Catering"), and two, the word is more likely to catch the searchers' eye because it is exactly what she searched for.

9. Use symbols $#@*-!

The majority of advertisers don't use symbols in their headlines. Using a few where appropriate can make your headline stand out as searchers scan the page. Note that I mean "where appropriate" very loosely... I test pretty much all of my headlines with a question mark at the end at some point.

Photo credit: try_to_touch