I was stumped as well, but a sucesfull trip to VGT (or several) turned him into a favourite class of mine ^^
Here's what you do, and what you capitalize on:
a) You start with LEMISI
1) If you hit it a bunch of times you scout out pretty much all the glyphs, a few powerups, all the subdungeons, all the altars and possibly the boss. The boss scouting has a low priority on LEMISI so it's not guaranteed, the rest pretty much are. The "scout X" preps were deemed to strong and disruptive to intended gameplay (and were overshadowing other preps by a wide margin I bet), and starting with LEMISI lets you play like you prepped a bunch of them at once. It costs some blackspace, but since you know where most important things are - you end up saving a bunch more. This is huge on it's own. Don't overdo - once you have enough scouting to make a plan refer to step 2
2) Every time you hit a CP threshold you get the effect of a STR potion. You can ussually only prep one, and it gives you an advantage while spiking a monster. Having a bunch available through glyph conversion is awesome and lets you level like a complete boss - especially since you know where all the fuel is (and if you go around picking glyphs up, you can also find targets).
Paradigm is - use up all you mana (fireballing, poisoning, endiswalling, slowing...) then convert a glyph, then hit whatever you're fighting for a big punch.
The initial LEMISI? It's your first CP threshold pop, your "scout everything" and your first free STR potion.
b) You have free STR on CP threshold, and you can pad out your CP with glyph use?
This means that the optimal way of leveling also lets you hit conversion thresholds, even if you prepped extra glyph. You use glyphs a bit to empty your mana, and then when you convert just about any conversion fodder item (like rock heart or viper ward) to spike something - you're guaranteed to hit a threshold even if you're a human
Don't force a CP pop through glyphs use, combine the two things!
Since your free STR potion bumps your base damage for one hit and humans give a bonus to % dmg, they make the best transmuters in my expirience. Dwarves are also a good bet - especially since using B2P also gives you CP (and you can go really silly with a Drac worshiping dwarven transmuter if you find B2P)
You can usually convert a glyph for an instant STR boost, otherwise pad out the bar, and convert... anything, really. If fighting somethign would take two hits - pad out, convert conversion fodder, hit, convert a glyph, hit again. If you're human that will probably leave you with a +20% dmg after the spike ^^
And that's pretty much it. Taurog and GG reward glyph conversions (and so does Drac to a degree), so you can combine that with your usual routine. Once you get the hang of it, it becomes obvious that some of T's advantages are in fact stupefying ^^