Tags are a powerful tool that helps to sort and filter all records. If you are already using all picklists and you cannot create more, use tags to categorize the record to other groups.
You can use Tags with all records in the CRM.
Step by step:
Open the record detail (e.g. Account) and click on the Tags icon at the bottom part of the record.
Type in the tag name and save it.
Intelligent code completion of already existing tags is available when entering a name.
Use the Advanced Filter to search for records with tags.
Set the tag name and click the Apply button.
Only the accounts marked with the particular tag will show in the filtered list.