I think you may be oversimplifying something that this is really not that simple. Many folks on this forum, for example, have literally spent years developing and polishing their strategies and practices based on what they see happening in the accounts they mananage day to day, week to week, month to month, year to year.
If I were to boil it all down, I might be tempted to say meet or exceed the expectations of the person who searches on your keywords and sees your ad, every single step of the way.
One of my favorite resources on how to think about AdWords, and, then, how set up an AdWords account in an informed and organized way which is likely to lead to better success is this page from the AdWords Help Center:
Tips for success
The topics covered on this page - which, in my opinion, are essential to using AdWords effectively:
1. Identify your advertising goals.
2. Organize your account for maximum effectiveness.
3. Choose relevant keywords and placements.
4. Create straightforward, targeted ads.
5. Optimize your website for conversions.
6. Track your account performance.
7. Test and modify your campaigns to get the results you want.
I hope that proves to be at least a bit useful.