Pay Per Click (PPC) advertising – placing text ads based on keywords or phrases on search engine results pages – has become a popular tactic to drive targeted traffic to websites. Many online merchants find it an effective way to market their products or services, especially once they’ve learned the ins and outs of putting together a PPC advertising campaign.

Here are a number of factors – some basic and some new – to consider when developing your PPC program:

Research your key words.

By paying close attention to your search words or phrases, PPC advertising can work for any size budget. But before bidding for a specific keyword, research the average price for that word by consulting a Keyword Price Index (KPI).

You can walk through the keyword process, including the KPI, with the assistance of free word and phrase generation tools from Google, Yahoo! Search Marketing or SEO Book. The cost of keywords can change quickly and often, so it’s a good idea to monitor your keyword prices on a regular basis.

Be specific when selecting keywords and phrases.

Because you pay per click, avoid vague words and phrases that result in clicks from consumers who aren’t really looking for what you’re selling. Be specific. Put yourself in the shoes of potential customers. What keywords would they search for?

It’s smart to use keyword phrases – referred to as “long tail of search.” For example, an interior decorator looking for linen Roman shades would type in “linen Roman shades” rather than entering “shades” into a search engine. The shorter tail search – only the word “shades” – can yield thousands of irrelevant results, including sunglasses. The long-tail method can save you from an expensive bidding war over common terms, making PPC advertising more affordable.

Consider using vertical search engines.

If you sell goods or services in a very competitive landscape, a PPC advertising campaign with a vertical search engine rather than a general search engine can be a winning option. Vertical search engines focus on one particular industry to deliver refined, market-specific content for niche users. In a recent study by Convera, nearly 90 percent of professionals said they believed that vertical search engines would offer more relevant content than popular internet search engines.

The focused nature of these sites means there’s likely to be competition for the same keyword(s), so get specific with your terms. Leverage the ‘long tail’ principle and bid on phrases. Remember to include common misspellings. For example, a lighting company specializing in iridescent lighting may want to purchase terms such as “irradescent,” “erradesent,” and “irridescent.” Sites such as SEO Tools can help determine common misspellings of keywords. And be sure to think about how your target audience searches for products, using their terminology, not yours.

Use PPC to promote seasonal items – and products in sudden demand.

PPC is also an effective tool for “blitz” advertising campaigns to promote seasonal items. If you sell water skis, you might consider boosting PPC keyword spending in the late spring and ending the campaign during the tail end of summer when, presumably, most people buying water skis have already done so. Seasonal blitz campaigns tend to be crowded, though, so the price for your keywords or phrases is likely to rise. You should factor this into your promotional budget.

Quick-response campaigns are also a natural fit for PPC advertising. A typically low-search product or service might see demand explode in reaction to an unforeseen event. For instance, Santa Fe doesn’t normally get much snow, nor does snow pile up on the ground. But late last year it was hit hard, and snow removal suppliers could have used the opportunity to alert emergency response teams that they had needed equipment in stock.

In about two hours, these suppliers could have targeted the Santa Fe-area response teams using a blitz keyword PPC campaign. And then, once the roads were cleared, the online campaign would melt away with the snow. These quick-response opportunities may only last days or hours, so effective campaigns require you to move quickly – far more quickly than any other type of advertising.

What to remember when using PPC.

If you decide to use PPC advertising, monitor it closely and often. Choose your keywords carefully. If you don’t, you run the risk of generating a large number of clicks from generic searches that may not lead to sales, effectively burning through your ad budget without seeing results. But with the proper attention, keyword selection and monitoring, PPC advertising can be a rich source of leads and sales for online merchants.