Spitfire Recognition

I wondered whether any of you have any tips on how to determine what particular mark of Spitfire or Seafire one is looking at. There are so many different variations I get muddled.

I can think of the following recognition points, but maybe the cognoscenti can suggest others.

1. Number of prop blades.
2. Cockpit: Malcolm hood or bubble
3. Armament: 20 mm cannon or machine guns.
4. Wing tips: clipped or not
5. Number of engine exhaust covers

I thought of building my own spreadsheet or flowchart, but wondered if this sort of thing in print or on the internet somewhere.

Bob