I can tell you how I trained my bitch to retrieve, it may not be to everbodys taste but worked a treat for me!!
She, to begin with was a muncher too. I bought a whistle, one of those small horn ones, and tooted it once (in the house,) when she came to see what it was i gave her praise and a treat. Then after she went away I did the same, reward and praise, BINGO in 2 days dog would come to me in a flash when I blew the whistle. Did the same on a walk and got the same response.
I then moved onto throwing a dummy with fur on it, held the dog back, made her wait, then sent her for it,