I wish I had known these things about Adwords prior to working on my first campaign.  Some are basic data integrity points that could save headaches; others are knowledge of Google’s default settings that could save money.

1. The default targeting setting for a new campaign is Global (as in, the entire world), with Google Search, Search Partners, and Content Network opted in.  Be sure to set your preferred geographies and network types before turning on a campaign.
2. You won’t always spend your daily budget on a campaign. It’s a cap on expense, not a guaranteed expenditure.  Instead, the amount you spend for a given campaign is based on the search volume, click-through rate and CPC.
3. It’s possible to spend more than your campaign daily budget on a given day. Google allows up to 20% overage on a given day.
4. Changing an ad deletes your history for that ad (or makes it really difficult to determine how it’s done over time). Instead, create a new ad and pause the old.
5. Changing a keyword (or its match type) makes it difficult to track performance over time. Instead, start a new keyword and pause the old.
6. Prior to the latest version of the interface, it was really difficult to tell what the geographical targeting is for a campaign.
7. Changing the geography of a campaign frequently is another data integrity nightmare. Instead, start a new campaign focused on that second, non-overlapping geography.
8. Match type is critical; shorthand for exact is [exact match keyword] and phrase is “phrase match keyword”
9. The Google AdWords conversion tag is not the same thing as Google Analytics.  Until they pull integration out of beta, use both just to be sure.
10. Google’s Content Network with Flash ads tracks View-through conversions.. which is really cool.