Many cat lovers will tell you that part of the attraction of cats is their independent nature. Dogs will pretty much adore anyone who pats them on the head in a friendly fashion, while most cats are much more choosy in who they bestow their adoring gaze on. This independence also means that they make their own decisions on when they will take any notice whatsoever of what their adopted human is telling them to do.
You cannot reliably train cats to obey a command - with a bit of love, attention, and a combination of aversion therapy (the trusty water pistol approach), distractions and rewards, you can arrive at a co-operative, and rewarding relationship.
There are four main methods to persuade cats to what you want.
1. Reward them. For example, our cats will come racing across the estate to come in for the night when we call because they know we will feed them as soon as they come in.
2. If that doesn't work, try some reverse psychology. For example, one of our cats occasionally finds the prospect of chasing moths in the garden far more interesting than getting fresh cat food. So I shut him out, engage in cat food tin noises and then try again. And if the moths are particularly entertaining that evening, I shut the door again and get our other cat to make exited 'I'm getting fed meows' right next to it - the rebel is generally ready to come in by the time I try again.
3. Distract them. If your furry f(r)iend is attacking your prized houseplant, clap your hands, or shout 'Oi!' to get their attention. Once they've stopped what they are doing for a few seconds, move them away from the plant, get out their favourite toy and play with them. On no account start playing with them while they are engaged in shredding your plant, or this will rapidly become their signal that they want a game.
4. Squirt them. If they have decided that your plant is so much more interesting than you clapping and going 'Oi!', and no amount of shooing them away is preventing them from immediately leaping right back up, get out the trusty water pistol or other water squirter and do the deed. One squirt followed up by a few hard glares if they even sniff the plant again over the next few minutes generally does the trick.
Important point to consider are:
You need to pick your battles. Our cats are happy to come in and get fed at night, but would look at us with disdain if we attempted to call them over for a pat when they're happily curled up on the other sofa. If we persisted in attempting this, I'm pretty sure they would soon start ignoring us all together.
Any reward, distraction or aversion therapy has to be applied while the behaviour is being performed or your cat cannot easily make the connection. So it's no good feeding your cat half an hour after he's come to your call, or squirting him after he's stopped mangling your plant.
You can't be around 24/7 to protect your plants or furniture. If you're leaving them indoors, you must make sure there's plenty of other things to do than trash the place. Provide access to high view points, hang bird seed outside the window, leave ping pong balls and catnip-sprayed toy mice lying around the place, provide them with a scratching post, cardboard boxes to squeeze into etc.
Finally, be aware that training works both ways with cats. For example, one of our cats has got us trained to sit on the end of the bed for a proper cuddle, as this is the only place (for some obscure reason) that she feels comfortable sitting on our lap. Neither of our cats have managed to train us to feed them on demand (though my other half occasionally wavers on this one so they keep trying), let them in or out of the house at early times of the morning when we'd much rather be asleep, or to wake up and wave the toy goldfish around for them in the middle of the night. No matter how cute they are, or how loudly they plead, be careful what you cave in to, because as soon as you perform the behaviour your cat requires, it will try that tactic again as it obviously works....