Start with toys and treats your dog already loves to create positive associations.
Say "take it" when they pick up item, then "give" when they return it to hand. Reward both steps.
Gradually step away so they have to move towards you to give the item back.
Daily short fetch sessions reinforce the behavior better than long occasional ones. Keep it fun!
Use consistent verbal cues like "fetch" and hand signals so they learn the chain of events.
If they struggle with holding the item, try different textures and weights to find one they can grasp.
If they don't bring it back, move closer or show excitement when they do to motivate them.