A friend passed this link to me "You should marry me…now! What to tweak and test in your call to action" from an article posted in September 2010 by Email Marketing Reports.
And I think there are some very useful points made about reviewing your call to action in emails. While not everyone can be Google, there are some useful examples that we can all remember when writing emails or email newsletters.
Consider:
1. wording
2. location
3. coding and format
4. shape, size, colors and highlighting
Read more resources for copywriting.