I'm not sure of this will exactly answer your question. If not, reply in this thread with @me and I'll see it.

Inspiration is the form of xp that refers to leveling the crafting skill lines. While the game used to list inspiration gains...like when you turned in a writ...they took that out, maybe because it was confusing. There's no where that says like "you have 25,500 of 75,000 inspiration for your next smithing level."

Levels

Therefore, the best way to see your progress is simply to look at the level meters in the skills menu, which also pop up as you're earning inspiration by deconstructing or building items. Eyeing those and how they change is the best way to get an idea of how much the activity is worth. But as a general rule, you get the most inspiration from:

- daily writs offer a decent chunk, plus the rewards almost always more than pay for the cost of making items.
- Smith, wood, cloth: deconstructing items, the higher quality the better. Don't deconstruct items you've made, nor do you really want to decon stuff you've stolen from like towns and guild halls...it rewards crap inspiration. Mob drops from delves and dungeons tends to produce the best gear to decon, along with intricate items rewarded from reward containers.
- Provision: just grind two item potions, the higher level the better.
- Achemy: stick with two item poisons/potions here too.
- Enchanting: runes you pick up in the world are the best, the higher quality the better. However, you need SO many this can take forever. To grind faster, buy a bunch of denata to make blue runes. You want to craft with one toon then move to another to decon, as deconstructing your own glyphs stinks.

Ranks

You ask about rank, which is different than levels. The level refers to the skill line level from 0 to 50. Your rank is determined by how many skill points you've spent in the first passive in each trade line. In smith, for example, you start as rank 1, allowing you to craft up to level 10 gear. When your smith LEVEL is high enough, you can spend a skill point in this passive to increase to RANK two, allowing you to craft up to level 19 gear. Then 29. Then 39, and so on.

Increasing your rank will:

1. Allow you to make higher level gear
2. Nodes in that skill (i.e., ore nodes for blacksmith) will half be determined by your trade rank. So if your rank allows you to use dwarven ore, half the nodes you see in the world will be dwarven (the other half are based on the character's level.)
3. Your rank determines what your daily writs ask for, and where they drop. Rank 1 players in smithing get writs asking for iron items that are dropped in Auridon. As soon as you increase to rank two any new writ will be for steel and drop in grant wood, then when you spend a point to go to rank 3 your writs ask for orichalc items dropping in greenshade.

Tips:

Feel free to level the lines as quickly as you want, but if you plan to do writs it's helpful to keep your rank in line with your player level, and if not at least keep the ranks close to one another. For example, if you increase your cloth, wood and smith lines to rank 4 all at the same time, the mats you find will match and the writs will drop in the same place.

Older guides might suggest that you not increase craft ranks faster than player level, as in being a rank 10 smith if you're only a level 40 character. This was because it used to be that nodes would then be for mats above what you could wear, so it was hard to earn like full leather for armor if you were a high level crafter. This should not be an issue with One Tamriel, because of the 50/50 system.