If you are constructing custom applications that interact automatically with the Google AdWords API web services:
Use the KeywordEstimatorService to estimate traffic for campaigns, ads, and keywords.
Estimate traffic for new keywords before adding the keywords to an AdGroup.
Consider raising and lowering your bids (maximum CPC) in code until you reach the desired level of impressions.
Consider using CPC, CTR, impressions, position, and not-shown data as input to a business intelligence module that makes automated decisions about what ads to run.