When I started learning to make French pastries, I bought the little cake decorating set you see everywhere. It came with a reusable bag and a nice selection of tips. Cleaning that bag was a real pain.
I’m now using large 20-inch disposable bags made by KopyKake that I purchase from my local cake decorating shop. In addition to disposable, the main advantage is that I turn the top half of the bag inside out and it completely covers my forearm while filling the bag. (A professional pastry chef taught me that trick).
I do still use the tips that came with that cake decorating kit.