When training a cat for behaviors there are some things you need to take into consideration. Aggression, especially in older cats, can be caused from illness or other cats in the home. You may want to contact your vet to have your cat checked out to see if it’s alright at this time to train a cat.
Depression and anxiety can play another part in trying to train your cat. If a cat is separated by a recent owner the cat can become depressed. Stress is not uncommon for a cat. If you think that your cat has depression or high anxiety, this would be a good time to take him to the vet. Vets can talk to you about some of the things that may be causing this. There are also medications that a vet can prescribe for the cat to help with depression and anxiety.
Never hit a cat for punishment, he will learn to fear you, and fearing will be a behavior you will not be able to control or retrain. When they do something that is not right, ignore the problem unless you catch them in the act, you can associate a noise with that behavior you don’t like, or in a stern voice tell them “NO”.
If a behavior is becoming impossible, you may have to resort to the baby proof home, all containers that have food in them have a lid on it. Make sure that the counters are clean and have nothing that a cat would want to play with.
You will want to start training your cat or kitten almost immediately after you get them. This will stop many unwanted behaviors and hopefully not let any new bad behaviors to start.