I buy chicken on sale.
Sometimes it is whole chickens sometimes pieces. I then roast them and wait till they are cool and shred them. Put the shredded chicken in a pan with some canned roasted tomatoes and taco seasoning and cook down. You can keep the chicken in a crock pot so it stays warm. When you go to serve have some shredded lettuce, tomatoes, refried black beans, sour cream and some cheese. I do it with the mini taco shells they come in a pack of 24 and since it is going to be a potluck 1 or 2 should do a person or you can bring tortillas chips and they can make their own chicken nachos.