With the chicken I was always told (like peachesmum says) to boil it in clean saltless/oilless water then leave it to cool in the fridge for 10 minutes. Make sure you are using fresh chicken and not chicken from a packet because this will have a lot of preservatives. The chicken needs to be free of anything added like salts, oils and flavouring.
Other than that uncooked pasta, boiled rice, lentils, a very small amount of carrots or broccoli, most nuts (ask if you are unsure though), cress, bird seed, baby food, porridge oats, boiled/scrambled eggs with nothing added to them... Always feed them in moderation though so in equal amounts and don't give your hammie more than it needs