I generally look to buy herbs between 20 and 30 gold a stack. Your server might be different. If you can get them cheaper, all the better for you. If your glyphs sell for more, then you can afford to pay more. I usually count on getting 6 inks (this is a bit low) out of a stack of herbs. That's two glyphs per stack...so glyphs will cost between 10 and 15 gold to make. Thus, my threshold of 15.
As I mentioned in the previous post, inscription isn't for your average player. I noted, you'd go mad trying to put all the auctions up by hand. The basic blizzard auction house ui is equally poor in design. It's natural safeguard of conforming every buy, prevents us from buying the quantities we want quickly. As the goblins say, time is money, friend.
To combat this, I use an addon called auctionsnatch. I am not entirely sure if TSM does this function or not, but because I've used auctionsnatch in the past, I continue to do so. Basically, what it does is search the auction house for items on your list and it filters them out if they are too expensive. It is honestly alittle buggy but the best addon for the job. I can click very quickly and buy massive amounts of goods. If you've ever sold massive quantities of materials and seen them sell super fast...faster than anyone could click the confirmation button--they are probably using an addon similar to this.
Random gold making tip--some people use this addon to search the auction house for massively long lists of things that aren't sold often. Instead of manually typing in X item and Y item every day, you simply search whenever you at the Auction House. Not what I use it for at all, but still a very powerful way of finding deals.
I tend to use 4 inscription bags to hold inks/glyphs, so herbs become a problem. In order to combat this, I actually use herb backs to hold herbs. Starting out, this won't be a big problem.
Once you've lined your bags with herbs, you can begin the milling process. If you are doing many different types of processing (prospecting, milling, and especially disenchanting, I suggest the Addon Panda. It provides a great interface for this type of grunt work.) If you are only milling or prospecting, then you really don't need it. You can make a macro to do it.
The macro reads as follows:
/cast milling
/use whiptail
You can then add any number of other herbs after whiptail. Say you also get cinderbloom cheap, then add /use cinderblom. There's a few other quirks. It looks at your first bag, then finds the first herb, and checks to see if there are 5. If they aren't 5, then it won't go. So if you buy an odd number, say 97 whiptail, you need to put the last 2 in their own slot away from the first or it won't run.
Don't get me wrong this is tedious work. I usually watch a movie or television while doing this. I basically turn myself the other direction and click one button every few seconds. With my attention elsewhere, I find less work than actually farming.
Eventually your bags will look like this. I usually will remove the inferno ink into the bank and continue onward. Naturally, if you aren't buying massive amounts of materials, you won't have this problem.
Once you've milled all your herbs down, you want to stack as many pigments as you can in your bags. Creating thousands of ink, takes huge amounts of time. Sometimes as long as 45 minutes. Thankfully, you can afk during it--completely. You set it to autocraft and then go grab a snack or do homework or laundry or whatever else you've been meaning to do.
So now, you have some amount of ink. What to craft and how to decide what do craft? Thankfully TSM, does the heavy lifting for you. Just like we had to set the rules for posting, we have to set the rules for crafting.
The first settings are about how many of each glyph do you want on hand? I only want a thin layering of glyphs. During wrath, at my high point, I had 16,000 glyphs and it took more than one character to manage them all. These days 2 of each glyph is plenty for me. This prevents me from tying up too much money on inventory and it allows for spending so little time cycling glyphs in the mail.
You also have to decide how much profit is worth your time? At this point, I set a very high ratio of 18 gold to craft a glyph. You could choose a much smaller number, if you are willing to accept to work for less. The other settings aren't too important for our glyph making.
Once you've set your perimeters, then it is a simply business of clicking restock queue. You then match the number of inks and vendor bought items with the number required. After that, you simply click craft next.
One nice feature is it tells you the price of the materials and what at current market prices, they'll eventually sell for. This isn't foolproof because markets change radically, but it gives you a rough idea what you might gain. In the example shot, 5826 in estimate profit, over 1271 in costs, suggests 458 percent profit! So for each gold I spend in materials I am likely to get 4.5 gold in return.
Naturally some of the glyphs don't sell quickly or often. This is alright because I'll never gamble more than crafting 2 of a given glyph. Thus, after that first gamble, I never need gamble again until it pays off.
This post and the last covered the basics of glyph making--how to make groups, how to post and cancel, how to mill, how to know what to craft, all in an efficient manner. Once your infrastructure is set up, then really this is all you need to know. Of course, once you are established, there's surely more we can delve into.