For tea, I just leave it out in a dish on the counter to dry over a couple of days.

I think dried mint is like dried hay. Freeze it instead. Best to chop it first, and make a flat pancake of it. Freeze pancakes in layers divided by plastic wrap. It's easy to snap off suitable-sized pieces of the pancake as required.

Mints do dry quite nicely. You can hang them or spread them on screens or paper towels. Always dry it out of direct sunlight otherwise you're going to loose more of the volatile oils in the mint and you will have stuff with little flavor.

I'd suggest trying both freezing and drying. I personally like the taste of dried mints in teas but everyone is different. See what works for you and go with that method.

FataMorgana

Mint, basil, parsley, cilantro, etc.....I like to put a bunch in the food processor or blender with a little water, just enough to make a slurry, thick-like, and then fill up an ice cube tray and freeze it. When it's frozen pop out the cubes and put them in a plastic bag, and back into the freezer. Anytime you want some, just take out a cube. Batya

I always have had excellent success hanging mint to dry for tea in my nice, dry basement. Spearmint, peppermint, and mountain mint all retain their flavor just fine when dried.
As soon as the leaves are as dry as cornflakes, I put them into canning jars, label, and store in a dark place. If I have dried a lot of mint, I seal vacuum-seal the extra jars so it really stays fresh a long time. CK