There is not a single answer in my opinion. I like to focus on cost per conversion since I know what a conversion is worth to me. Another metric I like to wat

There is not a single answer in my opinion. I like to focus on cost per conversion since I know what a conversion is worth to me. Another metric I like to watch is total conversions. It's a balance between optimizing for ROI and optimizing for total revenue. If I can get 50 signups/month at $3.50/conv and can get 75 signups a month for $3.85/conv, I'll increase my bid so long as it increases my total revenue. CPC on the content network is useful for branding as you receive exposure every time your ad is displayed, even though you only pay when someone clicks. Are your keywords highly searched according to the https://adwords.google.com/select/TrafficEstimatorSandbox https://adwords.google.com/select/TrafficEstimatorSandbox? If so, you may have to increase your bid until you build an account history and quality score.