Facebook provides an easy way to invite your existing clients and contacts to your Page by importing your email contacts. This is a great way to kickstart your Facebook marketing.
On the old style page select Invite Email Contacts in the right sidebar. If you have implemented the new Timeline – more about that here – select the Build Audience button on your Admin Panel then ‘Invite Email Contacts…’. Then Select ‘Find friends’ next to your email service. You can then suggest to your contacts that they should like your Facebook Page.
Note that if you have 5000 or more Likes the above is not possible.