This is a World of Warcraft Inscription Guide that will level you from 1-450 if you don't plan on buy the mats for this guide you really should as it's a waste of time to collect them all with Herbalism. If you don't have the gold right now check out this gold guide.
You will have to mill herbs in order to get the pigments you need for creating inks. Here is a breakdown of what you can expect to get from certain herbs:
Here is the actual guide, good luck, have fun!
1-20
Ivory Ink - 1 Alabaster Pigment
20-35
Scroll of Stamina - 1 Ivory Ink, 1 Light Parchment
35-55
Moonglow Ink - 2 Alabaster Pigment
55-75
Armor Vellum - 1 Moonglow Ink, 1 Light Parchment
75-80
Midnight Ink - 2 Dusky Pigment
80-100
Glyph of Your Choice (Orange) - 1 Midnight Ink, 1 Light Parchment
100-105
Lion's Ink - 2 Golden Pigment
105-125
Glyph of Your Choice (Orange) - Lion's Ink, 1 Common Parchment
125-130
Dawnstar Ink - 1 Burnt Pigment
130-150
Glyph of Your Choice (Orange or Yellow) - 2 Lions Ink, 1 Common Parchment
150-155
Jadefire Ink - 2 Emerald Pigment
155-170
Glyph of Your Choice (Orange) - 1 Jadefire Ink, 1 Common Parchment
170-180
Glyph of Overpower - 1 Jadefire Ink, 1 Common Parchment
180-200
Glyph of Your Choice (Orange or Yellow) - 2 Jadefire Ink, 1 Common Parchment
200-205
Celestial Ink - 2 Violet Pigment
205-225
Glyph of Your Choice (Orange) - 1 Celestial Ink, 1 Heavy Parchment
225-230
Scroll of Agility IV - 1 Celestial Ink, 2 Heavy Parchment
230-240
Glyph of Dispel Magic - 1 Celestial Ink, 1 Heavy Parchment
240-250
Glyph of Cleaving - 1 Celestial Ink, 1 Heavy Parchment
250-255
Shimmering Ink - 2 Silvery Pigment
255-260
Scroll of Spirit V - 1 Shimmering Ink, 2 Heavy Parchment
260-290
Glyph of Your Choice (Orange) - 1 Shimmering Ink, 1 Heavy Parchment
290-305
Ethereal Ink - 2 Nether Pigment
305-345
Glyph of Your Choice (Orange) - Ethereal Ink, 1 Resilient Parchment
345-350
Glyph of Whirlwind - 1 Ethereal Ink, 1 Resilient Parchment
350-355
Ink of the Sea - 2 Azure Pigment
355-360
Scroll of Spirit VII - 1 Ink of the Sea, 2 Resilient Parchment
360-365
Scroll of Intellect VII - 1 Ink of the Sea, 2 Resilient Parchment
365-370
Scroll of Strength VII - 1 Ink of the Sea, 2 Resilient Parchment
370-375
Scroll of Agility VII - 1 Ink of the Sea, 2 Resilient Parchment
375-380
Snowfall Ink - 2 Icy Pigment
380-385
Glyph of Your Choice (Yellow) - 1 Ink of the Sea, 1 Resilient Parchment
385-386
Northrend Inscription Research - 3 Ink of the Sea, 1 Snowfall Ink, 5 Resilient Parchment
386-400
Glyph of Your Choice - 1 Ink of the Sea, 1 Resilient Parchment
400-401
Master's Inscription of the Axe, Crag, Pinnacle or Storm - 1 Ink of the Sea
401-405
Scroll of Stamina VIII - 1 Ink of the Sea, 2 Resilient Parchment
405-410
Scroll of Spirit VIII - 1 Ink of the Sea, 2 Resilient Parchment
410-415
Scroll of Intellect VIII - 1 Ink of the Sea, 2 Resilient Parchment
415-420
Scroll of Strength VIII - 1 Ink of the Sea, 2 Resilient Parchment
420-430
Scroll of Agility VIII - 1 Ink of the Sea, 2 Resilient Parchment
430-450
Northrend Inscription Research - At this point there is no point in leveling up past 430, therefore I recommend that you simply continue to do your research once you hit 430.