With aluminum you get all the protection you need from freezer burn in a disposable container.
These are cheap enough to get you started but since they are hard to reuse they will cost more than glass, plastic or silicone in the long run.
Some come with lids. If they don't than put a layer of parchment paper and then a layer of aluminum foil over the top of the pan, sealing the edges.
Why parchment? Because it can go in the oven. If you use plastic wrap you'll have to take it off before baking.
These pans are freezer to oven safe which is a huge time saver because you don't have to thaw your meals ahead.
As a general rule reduce the oven temperature by 25 F and add 50% more cooking time than the original recipe calls for if you don't thaw your food. You might need to cover the top with aluminum foil so it doesn't burn while the middle is cooking.
You can not use these pans in the microwave and they are awkward on the stovetop.
Aluminum can react to highly acidic or salty foods and discolor or 'burn' holes in the pan. This chemical react creates aluminum salt which is safe to eat, however, your food won't look as good and might taste metallic.
While foil pans aren't likely to break or tear they are rather flimsy and can wobble when full of food. Thus you need to keep them on top of a cookie sheet when moving them into the freezer or out of the oven after cooking.
If you're thawing food that was frozen in a foil pan, thaw it on a cookie sheet so it's easy to move into the oven or anywhere else you need to move the pan.
Once frozen aluminum pans stack very well in the freezer.