Contacts
This page lists some tips on using Apple's standard Address Book app. This syncs with the Contacts app on an iPhone if you have one. The advice here is mostly about using Address Book on the Mac but includes hints for Contacts on the iPhone.
Importing
Address Book can import information from other applications in vCard, LDAP Interchange Format (LDIF), tab-delimited, and comma-separated value (CSV) formats. The help file has more details on each method.
If you use tab-separated or CSV, the import function prompts you to map the fields at the time you import them, e.g. "skip this column; this column is the first name; this column is the home phone." This page has a screenshots showing how to do it.
Some people, who had difficulties with the app on its own, recommended a conversion utility called Abee.
Duplicating records
You may want to duplicate a record, e.g. to start a record for another family member. Simply select the existing record then copy and paste.
Searching
Address Book searches all fields, including notes.
To search or filter using a specific field, add a Smart Group from the menu: File > New Smart Group. This allows you to search the whole card, or to filter by the contents of a particular field.
Managing groups
You can create a smart group of all contacts who are not members of another group. This could find e.g. new contacts that have come in from syncing with another device.
To select multiple contacts, in order to drop them into a Group, hold the command key (marked with or ⌘) as you click. This is a standard Apple keyboard trick which works in many programs; Windows copied it but uses the Ctrl key.
Dialling follow-on numbers
You may want to dial business numbers followed by internal telephone extensions, or standard responses for a customer service line. To automate this on the iPhone, you will need to insert a pause before the follow-on number. Insert a comma for a 2-second pause, or multiple commas for a longer pause. Alternatively, insert a semicolon before the extension, and the phone will wait for you to press the "Dial" button again when the answering service is ready.
To insert these characters directly in the iPhone Contacts app, edit the number and press the +*# button, then choose pause or wait as required.
Credits
Contributed by Neville Reid, incorporating hints shared by various people on the Mac Ministry List, October 2011–November 2012.