On Mac: 

• Go to the contact list
• Click "Filter" button on the toolbar
• In the window that appears select the field you want to filter by: Name, Age etc.
• If the filter conditions available, specify them: greater than, less than or equal to
• Specify the value to compare with in the last field
• To add more comparison conditions, tap on "+" button under the condition
• Save the made-up conditions as a template to quickly apply filter some other time

For example:

• You'd like to filter all men over 30 years old in your contacts
• Open Filters
• In the first field select Age
• In the next field select "greater than"
• In the last field specify the value to compare with - "30"
• Click "+" button to add new condition
• In the first field of second condition choose Gender
• In the next field of second condition select Male
• Click "Apply" button
• Now in the contact list you'll see all men over 30 years old

On iPhone or iPad: 

• Go to the contact list
• Tap on "Filter" button in the toolbar
• In the window that appears tap on "Filter by" 
• Select the field you want to filter by: Name, Age etc.
• If the filter conditions available, specify them: greater than, less than or equal to. 
• Specify the value to compare with in the last field.
• To add more comparison conditions, tap on "Add Condition" button and repeat the steps described above.
• Save the made-up conditions as a template to quickly apply filter some other time

For example:

• You'd like to filter all men over 30 years old in your contacts
• Open Filters
• In the "Filter by" field select Age
• Under the "Filter by" field select "greater than" 
• Specify the value to compare with - "30" 
• Tap on "Add Condition" button
• In a "Filter by" field choose Gender
• Under the "Filter by" field select Male
• Tap "Done" button
• In the window that appears you'll see all men over 30 years old

On Mac: 

• Configure the filter conditions. Please ref. to "How to configure filters"
• Click "Save as Template" button
• Enter the template name
• Click "Save" button to save changes
• To use saved templates go to the Filters and select the necessary template from the drop-down list at the top of the Filters window.
• Click "Apply" to filter

On iPhone or iPad: 

• Configure the filter conditions. Please ref. to "How to configure filters"
• Tap on a "Save as Template" button
• Enter the template name
• Tap "Apply" to save changes.
• To use the saved templates go to Filters > Tap on "Choose template" button and select the necessary template.
• Tap "Apply" to filter

On Mac: 

• Open Filters
• Click on the Templates drop-down list
• Click on a preferred template in the drop-down list to use it
• Click "-" button near the template name in the drop-down list and confirm removal to delete it

On iPhone or iPad: 

• Open Filters
• Tap on Templates
• Tap on a preferred template to use it or swipe left and confirm removal to delete it