How you do it is probably easier than you think - just know your animals and their behaviour. Then you just keep the camera nearby and take a couple of snaps when they're out and about. That's literally all I do. Our camera isn't even that good any more, though it was when we bought it, and I'm going to start looking for a new one. Anyone can take good photos with a very small amount of practice! I do love the little tongue sticking out though, she looks mischievous It's a good example of knowing your animals though, when this doe is heavily pregnant she will occasionally lick the side of the tank (goodness knows why) and some of her young babies follow suit. Complete nutters or what?!
Yes I keep and breed harvest mice. They are captive bred and it's legal to keep them. They're not endangered officially, but numbers are declining in the wild mainly due to loss of habitat to new farming methods. They're fascinating animals and I like it that they are mice yet quite different to the fancies.