The «Mastering Oracle Trace Data» from Cary Millsap is a great book about performance in general, and about how to work with trace data. The second edition have several new chapters adding valuable knowledge to both developers and DBAs. This is one of the books that you really should have in your bookshelf.
A few years ago I also had the opportunity to join one of Cary’s classes in Oslo. This was a one day seminar the day before leaving on the OUGN spring seminar – «the boat». Since this day I have been a regular user of the Method R software, and especially the Method R Profiler.