I used to Use DBCC SHOWCONTIG quite a bit for looking at fragmentation but have replaced that with the SQL statements against DMV tables and functions, especially for partitioned tables.

DBCC REINDEX or INDEXDEFRAG, but again i've switched to using ALTER INDEX WITH REBUILD/REORGANISE.

DBCC ShrinkDB normally only after restoring to a db to dev environment with limited space or as an emergancy measure on a log file once its backed up if its very low on disk.