Any tips for ways to cook chicken breast for recipes that call for shredded chicken?
I keep both shredded/chopped chicken and pork in my freezer as kind of a "staple". For both, I tend to use the crock pot.

The easiest way (but certainly not the cheapest) is to toss boneless, skinless chicken breasts into the crock pot with a flavorful liquid. I tend to use most of my shredded meats in things with either a Southwest/TexMex or BBQ bent to them, so I often will use beer for the liquid and toss in some chili powder/onion powder/garlic powder or one of those taco seasoning packets.

If you're looking for more wide-ranging purposes, you may want to go with something more like chicken broth as your liquid. In that case, I'd also avoid seasoning it all that much as the destination dish might clash with or, for instance, if you add salt, might result in WAY too much salt in the final dish.

I usually fill the crock pot all the way with chicken and about half way with liquid.

Set the crock pot on low and let it cook all day until the meat is completely cooked and tender. I only make it this way when I can be around all day or at least can check in half way through the day because you want to "rotate" which meat is sitting in the liquid at least once in the process.

To shred, pull out the chicken and, using 2 forks, pull apart the fibers of the meat.

To chop, just toss it on a cutting board and cut into tiny bits.

I usually take the results and put them in a large bowl. Then, using a turkey baster, I add some of the liquid from the crock pot back into the shredded meat. You'll be surprised how much liquid it absorbs without getting "drippy".

I freeze mine in 1 pound portions in vacuum sealed bags and it works great.