You should have the clear cut answer to the following questions before you even think of automation:
What are your wants and needs?
Where is automation practical?
Where does automation pay off?
What are the expected benefits?
Criteria for make / buy decision?
What to automate, when to automate, or even whether one really needs automation are crucial decisions which the testing (or development) team has to take.
Developing a test automation strategy is very important in mapping out what's to be automated, how it's going to be done, how the scripts will be maintained and what the expected costs and benefits will be. Just like every testing effort should have a testing strategy, or test plan, so should there be a 'plan' built for test automation. When strategizing for test automation, plan to achieve small successes and grow.
Assure that the product is mature enough so that maintenance costs from constantly changing tests don't overwhelm any benefits provided.
Automated software testing requires time and resources before return on investment (ROI).
Source:
bblsolutions
wikipedia
methodsandtools
test automation snake oil