Honestly, if you make time for that, it is a tremendous help.
http://www.haynes.com/products/?searchType=vehicleApplicationSearch2&searchEnd=yes&sfID1=&sfID2=&sfID3=&year=2003&make=Mini&model=R53+Cooper+S&x=12&y=5
Well spent money. You don't have to read it cover to cover, BUT, it can help you troubleshoot, potentially diagnose, and deff repair. If you have never used a Haynes Guide, they are REALLY easy to navigate, and put things into terms where a monkey could do it, and not a NASA trained monkey
If you REALLY want to get into the ins and outs, without it being overwhelming, grab one for your year.
$30 gets you:
Complete coverage for your Mini Cooper, Cooper S, Clubman & Clubman S for 2002 thru 2011 (See specific years covered) (Does not include Countryman models or convertible top information):
--Routine Maintenance
--Tune-up procedures
--Engine repair
--Cooling and heating
--Air Conditioning
--Fuel and exhaust
--Emissions control
--Ignition
--Brakes
--Suspension and steering
--Electrical systems
--Wiring diagrams
You change your OWN oil ONCE and the book has more than paid for itself.