It is very important to first understand how the PP system works. Once you get that right, you will definitely do better. Always test different templates/colors each week. Make a note of CTR's on different templates. After a month or two, when you are satisfied with the CTR on a particular template, lock it in. Thats how I would go about it. Also, make sure to use the custom keyword addition feature. Add some good relevant keywords that make your visitors interested. Don't just copy and paste a google top paying list. Make sure that a particular word gets your interest into clicking for more details. Ideally you will be able to reach a stage where both, your keywords and CPC will set in automatically and the system will only bring your top keywords higher up for the visitor to click on. Importantly, once your keyword has set and all top links start appearing in the 1-5 link slots, do NOT change your keyword. Once you do that, the system again starts trying out various combinations and you could end up wasting time for the new kw to set in again and perform.
I mean it might take me pages to explain the system. But you could use the above tips as a launch pad.