1. Offer something in return

Sometimes you have to offer an incentive to encourage users to participate.  This may be a free gift, access to a report or inclusion in a mailing list.  They are giving you their valuable time or details, what are you giving them in return?

2. Define your intentions

Before a visitor commits to your call to action they have to see the direct benefit.  Before they respond to your request, they must understand what they will gain from following your instructions and what risks they are taking by doing so.

3. Have a small number of distinct actions

Deciding on the number of calls to actions is just as important as the action themselves.  Too many and you will leave the visitors confused as to what you want them to do.  Too few and you risk alienating a specific group of your visitors.By limiting the number of choices a visitor has to make you reduce the amount of mental effort required of them.  You should effectively guide the visitor through your site one step at a time. 

4. Use the correct language
A call to action should inform a visitor of precisely what you expect them to do.  Where possible you should try and include terms such as call, buy, register, subscribe, donate & add etc.  All of these encourage a visitor to take an action.To create a sense of urgency and push the visitor into an immediate action you should use additional phrases alongside the action words, such as:

• For a short time only
• Order now and receive a free report
• Offer expires 1st December

5. Repeat the call to action

A call to action should not be limited to the home page. Every page on your site should have a call to action of some variety.  If a visitor leaves your site without responding to any call to action it should be viewed as a failed visit. 

6. Measure the success of the call to action

Knowing when a call to action is having the desired effect is crucial to the evolution of a website. You need clear visibility on which actions are engaging with visitors (allowing you to improve on them) and also which aren't (in which case you may want to try something new).

Advanced tracking tools, such as Google Analytics, allow web site owners to set triggers on specific user events which will record when a visitor performs an action.