a good place to start for herbal teas is plant a lot of mint--spearmint, pineapple mint, lemon mint, peppermint, etc. Watch where you plant mint as it can get away from you. Harvest it all season and dry it. Other things you can easily harvest are hibiscus, if you live where they grow. Rose hips are generally gotten from old time roses like rigosa and wild roses, that have big hips. Just cut them in half, get rid of the fuzzy junk and dry the seeds and the peel. Sage is easy to grow, but I don't find it a pleasant tea, so I just use that tea medicinally. Raspberry leaves are good in tea, if you have an abundance of bushes. Dandelion root is pretty nasty tea, but very valuable for liver and gall bladder ailments. Chamomile is not a very easy herb to have because it takes a field of those babies to get much. So my advice there is to buy a # of this at San Franciso Herb Company. That's a lot of chamomile.
I make a tin of herbal tea mix for the winter and use it in my tea infuser. It consists of 2 parts mint (any kind), 1 part chamomile, 1/2 part hibiscus petals, 1/2 part raspberry leaves, 1/2 part rose hips, 1/2 part clover blossoms. For a really excellent treat, use some peach, pear, or apricot nectar , (or other similar fruit juices you've canned like cherry) . If you've got a sick person you must tend, make them a thermos of this, add a T of honey, juice of 1 lemon. If they're really under the weather, add a shot of whiskey. He'll be feeling fine at the end of the day.