Tend to know the basic characteristics of the various models before I go shopping so I suppose that comes under:
1) Reviews - from as many sources as possible
After that unless it's the bargain of the Century I'd have to
2) Not object to the colour
Then I'd suppose it'd be Test Ride (if I'm unfamiliar with the breed or it looks like the sort of bike you ought to test ride...) and all the other checks...
Colour at number 2....
shocking.