I had a lot of comments on my last post regarding Inscription, so I figured I'd follow up with a new post instead of posting a reply that would get lost or not seen.
For the power leveling question, I'd say it's up to you if you want to wait and do it all at once. I know it's how power leveling professions has been done for years, but it does miss the point of my last article.
The main point of my article was that Inscription is a great profession to level while you level your character because it is useful. If you wanted Engineering as a profession, I'd say wait until you hit level 70 at the very least and power level like crazy. It would give you more time to bargain hunt on the auction house for materials as a side benefit. Engineering has very little benefit to a leveling character, so why bother taking time away from questing?
Inscription is a great profession and it was designed well. The money making part of it is great, but if I wanted to play a game to just make money, I'd be a day trader in real life and not waste my time on making fake money in a game. I play games to have fun and Inscription helps in that regard a lot. I use it while I'm leveling. It helps enhance my character's performance, if you know what I mean ;)
So, in my opinion, if you have a low level alt and want to take up Inscription, start to level it now. I think you'll really enjoy it.
If you did chose to power level Inscription, I'd say just buy the herbs from the auction house, unless they are grossly overpriced or in short supply. You can also buy Ink of the Sea (if it's cheaper than the herbs) and trade it to Jessica Sellers for the inks you need for leveling. For advice on what addons to use, I'd say check out the Greedy Goblin's articles on inscription or Just My Two Copper's forums.
The third generation of pay to win
7 hours ago