We are training our two boxers (Max is 4 and Mia is 2 years old). I agree that basic obedience will lay a great foundation. Two other great things to train are impulse control and patience...they go hand in hand. I knew since before getting our two dogs I would need to train them on that from the get go.
Find out a comfortable distance from the chickens your dog on leash can handle (i.e. she knows they're there, but will still pay attention to you and respnd to commands). Work at that distance until you can move closer and closer. Training takes time and if it takes her a few months to move a foot at a time than so be it.
Do you know if your pup is food or treat or attention motivated? Use that to your advantage now for training. Unless your pup doesn't care about treats or toys..Then you have to move on to different training methods.
Both of my dogs have considerable prey drive. I have trained both of my dogs using various methods since pups from positive reinforcement treat focused stuff and more "harsh" methods from martingales and prong collars. I have found, in my own experience, positive reinforcement works in certain low-stimuli/low-distraction situations. I gauge each situation though..for chicken training I however combine treats and praise with e-collar training.
We live near farmlands and go on regular outdoor adventures like hikes and days at the river. After too many close calls with wildlife (deer, bears and coyotes included) I have since graduated to dogtra e-collars and will not use anything else nor trust any other method to break their focus, especially around other animals.
With the e-collar and leash on, since Max is used to training with it, on our first training day with the chicks loose in the yard he was able to come about 6 feet close without becoming too focused. Mia (our female) couldn't go any closer than 10-12 feet. They listen perfectly with the e-collars on, but since this is brand new training to them, we are working on finding a comfortable distance between them and the chickens. The collars are pricey but great investments if that means keeping my dogs and other animals safe.
Of course, find the appropriate training method for your dog. If your dog is "soft", a positive reinforcement method will be suitable. I own two crazy, high energy, stubborn boxers and after various incidences I had to match that level of intensity appropriately.