I apply a simple approach:

1/ State the objectives you want to achieve. They should be measurable e.g. % increase in signups, emails collected, etc.

2/ As @noelwesh mentions, create a checklist

3/ Measure the impact of each action in the checklist

4/ At the end of a 'campaign', evaluate what worked, what didn't, how to improve things, how to learn further.

5/ Iterate.