If you thought saying something useful in 140 characters on Twitter was hard work, good luck with the 95 characters you have available when writing a Google AdWords ad.

The constraint of the character count is just one of several challenges you will be facing when writing your PPC ads.

You will also have to put aside the way you approach writing regular "advertisements."

Contextual ads, whether delivered by Google, Yahoo, or any other company, are not standalone ads in the way that a newspaper classified ad is. In fact, your PPC ad is simply the connector between a desired keyword or phrase and a destination landing page.

So while you may have some wonderful things to say about your products or services, your PPC ad is not the place to try to cram your latest sales message into 95 characters.

A PPC ad serves a very specific function in a very specific way. Its purpose is simply to match the thought in a reader's mind and then move that person forward to your landing page with a click.

1. Always include a strong keyword in the title

When someone goes to Google and types the phrase "office coffee maker" and is presented with page one of the search results, you can be sure that his or her mind is already preset to recognize the phrase "office coffee maker."

Put simply, the reader has flagged and announced the exact phrase he or she will be scanning for. This is why you always want to include keywords in the tile.

Of course, you probably have more than one keyword you would like to be bidding on. As a result, you might want to set up multiple ad groups for a range of important search terms. Each ad is then optimized for a particular word or phrase. With Google AdWords, you can use the automatic keyword insertion tool, which can save you a ton of extra work.

2. Make your title relevant and compelling

The title is the most important part of any PPC ad. If your title doesn't work, then nobody will read any further or, more important, click on your ad.

Writing a strong title is really tough: In the case of Google AdWords, you have just 25 characters to work with. "Office coffee maker" takes up 19 of those characters, and you have just six remaining.

Ouch.

So what you have is real tension between the need to include search terms in your ad titles and the need to say something compelling and engaging. All in 25 characters or less.

As the writer being asked to work on a particular ad or group of ads, you might want to remind others on your team of the character limits, and suggest that they give you some of the shorter search terms to work with.

3. Use short words

Wherever you use a long word, there is usually a shorter word that will do the same job for you.

An "automobile" is a "car." A "giveaway" is a "gift." An "offer" is a "deal."

Whether you are writing a 25-chacater title or one of the two 35-character lines of body text, every letter counts. Using short words can give you two or three extra words to work with.

4. Be relevant and specific

Your ad is going to appear on a full page of search results, and it will be competing with every organic listing and every other PPC ad.

If your ad says more or less the same as every other listing and ad on the page, then it's pretty unremarkable—and your chances of earning a click are remote.

One way to stand out is to be narrow in your appeal by being very specific:

• Don't sell kayaks, sell 16-foot ocean kayaks.
• Don't sell headphones, sell Bluetooth stereo headphones.

The more specific and relevant you are, the more attention you will attract from people who really want to buy.

5. Be aware of the larger picture, and keep testing

Your PPC ad doesn't live in a vacuum. On the one side it is connected to your top keywords, and on the other it is connected to your landing page.

Among other things, this means you should always be testing your PPC ad copy. Try multiple variations. Say things in different ways:

• Try a hard sell and a soft sell.
• Test sensible against outrageous.
• Test a positive message against a negative message.

However good you think your latest ad version may be, you won't know for sure until you test it.

And this, ultimately, is all you need to know about writing great PPC ads: Just keep testing and testing and testing until you get ads that grab the attention of the right prospects and then convert best into clicks and sales.

Looking for more PPC advertising help? Check out Cracking the Code: Web Analytics for Paid Search Advertising, a MarketingProfs online seminar where you'll learn from popular analytics expert Avinash Kaushik how to start fast with PPC advertising and fix problems within the first 24 hours by focusing on the right metrics.