I dry dandelion leaves for a winter supply. Can't ever find enough plantain to dry any as they scoff it all so quickly!
I'd say you could use the same method though.
I pick mine with the roots intact and then hang them upside down on a clothes airer in the garage for about 5-6 days. By then they're mostly dry, but I then put them in wicker baskets loosley packed for another few weeks until they're completely dried out.
If you box them up too quick they get mouldy.
Once they're completely dry I put them in a dark container, but leave the lid slightly open so it still gets air around it.
You'll be surprised what they dry down to though - I did 8 carrier bags packed full of dandelions recently, and once dry they only filled a small bag!