segmentation types

Hi

All in our company we are using CRM 7.0 version.

I need one information on segmentation, can any one explain the segmentation how may types?

if i want to run a campaign for new customers what kind of segmentation we will use? how we will tagret the group of people. because in this verson we dont have profile set.

if i want to run a campaign for exesting customers from where we will pick the data in CRM 7.0 ??

regards

mohammad