One way to preserve the flavor of fresh herbs is to salt layer them, which is simply packing in a jar between layers of salt. I learned this from an Italian CB I had years ago - not many great recipes I kept, but I learned this method! You just start with a layer of salt, put a few layers of leaves in, sprinkle more salt, and keep it up, pressing down as you go along. Amazing how much will go in a small jar!
I only used it for epazote this season. I pulled the plants just before the first freeze, and had about 2 qts loosely packed leaves:
DSCF0379 by
pepperhead212, on Flickr
Here it is started, in a 10 oz jar:
DSCF0382 by
pepperhead212, on Flickr
And here it is finished, with room to spare:
DSCF0386 by
pepperhead212, on Flickr
DSCF0384 by
pepperhead212, on Flickr
As for herbs and spices that I buy dried, most of those I buy unground, except things that come only ground, such as paprika (unless you grow your own!), and, depending on how quickly I use them, I keep a jar of them in my spice drawers (easier to label the tops, and look down on them, than to try to find them in a cupboard, which is traditional), or those spice boxes I have specifically for my Indian spices and spice mixes. The rest of the large amount that I got I keep in a vacuum sealed bag, which keeps them very fresh tasting, and the few ground ones, or things I simply don't use frequently, I keep in a box in the freezer. The vacuum sealed bags flatten out greatly, so they don't take up much space. A few spices don't do well in this, as they are sharp (star anise comes to mind), and puncture the plastic, so I put them in a jar, with a couple of oxygen adsorbers, and keep them on the door of the freezer.
Things like the Indian spice mixes that I make, I make in small amounts, for the most part, except for a couple varieties, that are used in larger amounts. And at this time of year, when I start using them more, since it's getting colder, I make up a bunch of new batches, and throw out the small amounts of the others, which I probably had not used for several months.
Two online spice sources I use are
https://www.penzeys.com/
https://www.spicesinc.com/t-spices.aspx
It is amazing how much more flavor slices have when you get them from a place like this, with incredible turnover, compared to supermarkets (plus no telling how long ago those jars were filled).
Another source, more for chiles and dried mushrooms, and a bunch of other bulk foods:
https://www.myspicer.com/