What are your tricks for keeping brown sugar soft?

It might be crazy, but you can just make your own brown sugar when you need it. Use white sugar and add molasses to taste. You can make light or dark and you don't have to have a separate container!

keep it in the plastic bag and in the box. Stick it in the freezer! take out maybe 15 minutes before you need it, and it should be useable. Works good with light and dark brown sugar.

in a tightly sealed ziploc bag in the fridge. it's that simple!

You can go to a tourist shop and buy one of those clay things for $6.99 - and they work ! ... but you can also take a hammer to a $0.99 terra-cotta clay plant pot and put a piece in a mason jar, fill with your brown sugar, screw the top on and figure out how to spend the money you have saved.

I keep it in the freezer, which seems counterintuitive, but works really well. It scoops out pretty easily; we use it regularly for oatmeal etc and there's no waiting time. I weigh my ingredients, for what it's worth; not sure if you use measuring cups if this would be a harder storage method.

I read somewhere that a marshmallow works.

I have a "sugar fairy" (as we call it) - it's a little piece of unglazed clay stamped with a fairy that you soak in water for a bit, then keep it in the bag or canister with your brown sugar. The moisture from it keeps the sugar moist. Mine is similar to this: . If you google you can find directions for making your own if you have clay around.

Any air-tight storage container will keep it fresh and moist. I'm a big fan of the OXO "pop" containers for the purpose.

My mother puts an apple slice in her container.

What I learned in Home Ec: a slice of bread in with the brown sugar to keep the sugar moist and soft.