1 Are your treats high enough value? (Praise and food)
2 bye bye first
2 Ping Pong Pup! two people is better than one and more fun not really training
3 4 Gradually increase distractions
5 Mix it up (never lead on at the same time. make it wiggly walking.Its their job to stay with you and they watch you. not yours to stay with them
extra point to consider is yuo need to feel confident. It can be nerve wracking to let your dog off the lead for the first time or if they dont usually recall well. if you are nervous fake confidence as the nerves will rub off on your dog. if you are nervous they will be too. lastly to give you a little more resassurance while training you can attach a long line to your dogs collar or harness and drop it on the ground you can buy 10m 20m even 50 m lengths so your dog can get to quite a distance without you worrying about them. if they arent recalling you can pop your foot on the long line and then pick it up and bring your dog back.