- Start somewhere that has little or no distractions.
- Attach a long line (20 feet or so) to your dog's collar.
- Have a friend or family member occupy your dog while you go out the distance of the leash, or put your dog in a "Stay" position.
- Excitedly say your dog's name, followed by the command, "COME"!
- Reward your dog when he/she gets to you. Use several treats to encourage him to stay put.
- If your dog doesn't respond to this command, reel him/her in until the dog reaches you. Then give the reward. Eventually your dog will put two and two together.
An important thing to remember when training this command is to ALWAYS reward your dog for coming to you when called because this will help to ensure that he/she will come to you every single time. Even if you don't typically use treats as a reward, you should use them when using this command.
Also, remember that your dog doesn't speak human, so unless you are absolutely positive your dog will respond when you use the command "Come", don't use it. Find another word to use for the times that you're not sure. Words like "Cookie" or "Car Ride" might work. Don't practice this without the leash either. If your dog is not yet reliable, the leash will protect him/her from danger.
Here is a picture of Sami - Coming when Called.