Funny thing is - I'm not all that pro with gods, especially GG. I'll say what I do, but it might easily turn out that my routine is suboptimal
I only "discovered" that GG can be quite a piety farm a coue of days ago, I've been purposfully avoiding him as "that guy that always screwed me over" up till then
What I do one the "only GG and TT" rofile is:
1) Find GG, join him, and convert conversion stone (if I have it).
2) Level up on lvl 2 monsters, which is easiy after a conversion or 2. Before the lvl up, i make sure to get posioned/mana burned if possible.
3) If I can kill a lvl 4 monster, I go to step 4, if not, i kill a lvl 3 monster to get myself to lvl up off another lvl 3 monster.
4) When I'm lvl 2 I get a lvl 3/4 monster ready to drop, refferably from a physical hit, take humillity, get myself poisoned and manaburned if my HP would still allow me to get the killing hit on a lvl 4, then kill the lvl 4.
5) Keep killing higher lvl enemies, and getting poisoned/manaburned before every lvl up, and if possible, I get posioned mulitple times just before lvl up if I can manage to do it with helpmeh, untill I get absolution or decide I can't and join TT. This has 2 apporaches, using xp catapults where aproriate:
5.1) The one where you kill 1-2 lvl higher enemies to squeeze a little piety and a lot of XP. That's to avoid making them untouchable once I lvl up, and get myself xp un dungeons with lots of debuff enemies. I sometimes even kill equal lvl enemies, esecially in vicious dungeons, and i ofeten kill lover lvl undead.
5.2) Just kill monsters as high lvl as possible.
6) After I got enlightment, I try to figure out a way to to switch. It ussually invoves milking the map for any GG piety. I'll even convert potions if necessary. And If I'm sure I won't need the glyph/item (and it's hard to be really sure for some of them), I do the conversions while rushing englihtment, as they help me with lvling. I buy out stuff to convert at this point, not worrying about money. If it takes converting gloves of midas before you eat up popcorn, I do it.
7) Swap to TT.
Now, sometimes I get stuck without a way to kee the GG routine going, and swap to TT earlier to eat up popcorn, then swap back out, ussually with dodge and Tiki's Edge. I'll swap with to GG with poison only if I'll be only fighting undead untill the end. With lots of gold available you can jump between the gods, but this often means not getting Enlightenment.
If I'm joining him early:
First Approach: Join him, buy Tiki's Edge with gold, kill a lvl 2, keep going from there.
Second Approach: Get to lvl 2, join him, have more ease in wether you need Tiki's edge.
Third approach: Join him at 50 piety with GG, or when you run out into a dead end with GG.
Otherwise, you do what I just said. Sometimes you can skip poison, but if possible, do take it for the gold, and random piety benefits. I'd only skip it if there is nothing left to poison (only undead left).
1) I sometimes avoid Tiki's Edge, but getting Poison and Dodge increses your piety gain, and decreeses your piety loss.
2) You kill popcorn, obbviously
You can kill lower lvl fat stuff without piety loss if you can kill it in 2 hits with first strike on the last hit. You can allow yourself to get hit ONCE.
3) I ussually don't bother with using popcorn for XP catapults (and I should, I'm just sloppy around this time, it's a psych thing after being so carefull with GG).
4) With poison and dodge, and a good supply of piety, you can afford to lose some on being hit here and there. A doged poison hit give you 4 piety, getting hit ussualy only costy you 1 piety. Make sure you never go low with tribute, and if you get lucky you can actually stay level forever, or bleed piety so slowly that it doesn't matter.
5) If it's possible, especially against bosses that lower resists, I try to use his potion boon, at least once. It ussualy translates to getting 2 "free" hits in, so doing it early in the fight, esecially aganst debuff bosses, is what I do.
6) Sometimes, say against an undead boss, I sink all my gold into TT, and convert to GG after I've used all my potions, or all but 2 of my potions. The reason is that I can squeeze one healing from GG (15/25 depends) and one cleansing (5 if I haven't used one, 10 if I have), and still have 20 piety to be able to use my potions. If I have no potions, and i got to 100 piety with TT, i can get 2 heals of GG, but the boss has to be undead (because of the -10 using poison penalty).
That's about it, if anyone has any more tips, Id really love to hear them. Also, I'll try getting Absolution into my routine, as I don't ever use it (I save my popcorn for TT, maybe I could afford to "waste" the lvl 1 ones).