During tough economic times, marketers need to obtain the highest ROI on each and every campaign, and attempt to maintain their volume goals as well. That’s why right now you need to spend more on the methods that work best to convert browsers, and less on experimental campaigns that don’t necessarily deliver sales results. But blindly throwing more money at search advertising won’t deliver the type of results you need. Instead, smart marketers need to learn to spend more, while maintaining, or even boosting, overall ROI. To “spend more and spend better” on your SEM campaigns, follow these five simple tips:

1. Bid based on results, not on position. Early search engine marketing efforts focused on the position of your ads vs. the position of your competitors’ ads. There are important lessons to be learned from reading your competitors’ ad copy, but if you focus on whose ad is higher on the page, you are focused on the wrong thing. Business metrics like ROI or margin should drive position, not the other way around. For example, look at what a keyword has brought in value over the last week and divide by the number of clicks for that same week. If a keyword is worth $5 per click and you want to run at a 20% margin, you would bid $4.

2. Bid at the keyword level. Different keywords, even with slight variations, perform differently. We saw an example where the plural of a term sold for 50% more than the singular of the same term – and they were in the same ad group! If you have the click volume and the Excel skills to calculate bids for each keyword, bid more for the more effective keywords, gaining volume, and less for the others, saving money.

3. Bid separately for search and content. Did you know that many of the visitors clicking on your ad coming in from Google and Yahoo do not enter a search term at all? They come from the ads that show up alongside blogs, forums, email, or news stories from across thousands of web sites. Ads matched to this channel are known as “content distribution” ads. Different types of traffic have different conversion rates – and should therefore be bid on separately. A shopper who enters a product term in a search engine is looking for information or to buy that product; somebody reading an article is not necessarily as “intentioned,” even if they happened to click on an ad because it caught their eye. All three major engines allow you to enter separate bids for “search distribution” and “content distribution” ads to reflect this difference; content bids should generally be lower.

4. Test and optimize your creatives. Google will “optimize” your ads by showing those with the higher click-through rate more often. This is great for Google, but for the advertiser, you should be optimizing for ROI or revenue/conversion volume. Measure margin/ROI, or revenue/conversions, on an ad-by-ad basis – then pause those ads that are not doing as well.

5. Know your priorities. Are you interested in maximizing revenue? Or profit? Understanding your goals will impact every aspect of your search marketing tactics. For example, tail terms (e.g. “Ford f150 fan belt”) can be more profitable than broader terms (“Ford parts”). A profit-focused marketer will keep the extra money; a revenue-focused marketer will use the extra money to increase their effective budget, plowing it back into more competitive, pricier keywords.

No one said marketing was easy. Sometimes you just have to spend more to get the results you want – and even a budget-conscious CMO will agree to spend more on SEM if ROI remains stable or increases. In today’s heady economic times, every advertiser needs to find a way to spend more and spend better on the marketing methods that deliver the best results.

The tag line of one ad: “There are no female marines. Only marines.” And so it seems a different kind of behavioral targeting has hit the armed forces: “We never used to have much of a targeting strategy — we were just looking for 18-24-year-old men,” Lt. Col, Mike Zeliff, assistant chief of staff for marketing and advertising for the Marines Corps in Quantico, Va., told the Times. “Today, we are more niche than ever.”

Other branches of the military are launching behavioral targeting advertising campaigns too: the Navy uses the Web to recruit women for nontraditional jobs like aviation mechanics, placing display advertisements on search portals, movie sites and video games sites, the Times reports.

An account director with the Navy’s ad firm, Campbell-Evan, told the Times that women-only e-mail blasts had been a highly successful recruiting method.