Another way of checking is to use two camera/lens combinations and see how the exposure readings vary (having adjusted for different lens apertures etc).
I often carry two camera bodies and frequently find quite marked exposure readings - but with a random pattern (ie one is sometimes giving a higher aperture than the other but sometimes lower)!
The only reliable way I find, is really to review the first pic on screen before firing off too many more (if you have the time of course as animals/birds are masters at disappearing at the vital moment). I also try to take an 'exposure' shot anytime I am expecting something to happen (eg when in a bird hide) and have everything all ready and set up for when it does.
If only we could have done that in the days of film!
