You can create groups for the different types of mailings donors receive from your organization and add donors to those groups.
Go to Settings/Fields,Lists and More/Change GiftWorks Built-In Fields/Donor Groups
Select the All Donors SmartList and then click on Run a SmartUpdate from the Related Actions menu. Check the Groups to add donors to those groups. You can also create SmartLists of selected donors and add those donors to specific groups You can use the groups criteria to create SmartLists for mailings