If you advertise using Google AdWords (and many of us do), avoid getting into a bidding war. Google loves these auctions, but you’re just handing them your money.
A fight for keywords means that there’s also disheartening competition for markets. Who needs that?
Instead, advertise in a niche where you’re the dominant player. Not sure how to do this? Keep on narrowing the scope of your market description until you’re in a position where you’ve shed most of your rivals.
You’ll have the relevant keywords all to yourself, which means they won’t cost heaps. You may even be able to dominate the sector with natural, unpaid search.
Google won’t be impressed with your parsimony, but your pocket will like the result.