Set your dog up for success by initially training in a quiet place. Start indoors, in your garden, or in another enclosed space with some tasty treats in a pouch or your pocket. If you need to, get your dog’s attention with their name, then use your recall cue and take a step away from them. As they return to you reward them with praise and a tasty treat.
For recall training, use rewards that are exciting and tempting - especially if your dog has come away from something very interesting (such as a squirrel or another dog). Try making your recall exciting by throwing their treats out for them to chase, find and eat, or using play or games as their reward. Think about how you sound and appear to your dog when you call them. Use a happy, excited voice and welcoming body language (crouched down, arms open). Moving back from your dog as you call can encourage them even more.
You can practice off-lead as well as on-lead, but be careful not to pull your dog towards you with the lead as that might put your dog off. Let your dog work out how to get their reward - make it easy for them by showing them what you have to entice them to you!
Always praise your dog for coming back no matter how long it takes and reward them even more if they come back quickly. As your dog improves you won’t need to give them a treat every time they come back, but remember to reward them every so often to keep them motivated.