This is really very easy and everyone loves it:
3 or 4 chicken breasts, cooked (boiled, broiled, grilled, whichever you prefer, or similar amount leftover roasted chicken)
2 cups salsa
hard or soft shelled tacos
sour cream
grated cheddar cheese
guacamole (I just smash avocado and add salt or salsa)
Shred the chicken by hand - just tear it apart into small pieces - and place in a large pan. Cook on medium heat until warmed, add salsa, stir and cook until heated through. Serve with sour cream, guacamole, grated cheddar, etc. on warmed hard or soft shells. Super easy and very good!