Keep your cat inside for the first two or three weeks after you move house to give him time to learn the geography and become accustomed to the smells.
When you decide the time is right to let him out, withhold food for about 12 hours so he is hungry. If he already associates a particular sound with food so much the better. Choose a quiet time to let him out in the garden, ensuring that there are no other cats about. Go out with him and let him explore before calling him in for food.
Repeat the exercise several times, allowing him to go further and longer each time.
If your cat is spending time outdoors he should be microchipped or have some form of identification with his name, your address and phone number.
If you are not moving far, you may find that your cat returns to his old home. This is simply because he has not bonded sufficiently well with his new home and has picked up familiar routes during exploration of his new territory.
Ask the new occupants and neighbours to discourage him by chasing him or calling you to collect him.
In this way he will begin to recognise the new house as a source of food and shelter, both of which are being denied him at the old house.
This period of readjustment may take weeks and, in some cases, it can be months before he can be allowed outside unattended.