Ok here is what you do, to get top rankings and keep them for good. This requires a little bit of startup capital but after that the profits will be worth it. So basically you just need to outbid everyone. As you are at the top of the rankings you will be paying more, but your CTR will be much higher than others, as your CTR is higher, you will get awarded with a good quality score and decreasing CPC. Each day you can drop your CPC slightly whilst retaining that #1 position. You should drop it so that you are bidding 10c US more than the Average CPC of the previous day. Do this day by day until you are sitting at the lowest bid possible for that market. Usually this will be around 50c-$1 in a reasonably competitive market. But as you know some are much higher. To see more great Adwords tips like this one check out my site.