Arfie,
It is better to train vinecraft before spirituality until you have it at level 7. It is important to get your level 7 spells before you change roles. It is much easier to train up at the guild except for the 1st level because it only takes 1 point.
It is also better to learn induvidual spells from experience then from spellbooks because you do not get any mana boost from spellbooks.

Arfie,

Training at guilds doesn't matter a whole lot in the long-term play of the game. Before you get near the end, you'll be at least level seven in every spell school you can get.

That being said, I'd get up to level 4 Vine ASAP, and then go to level 7 Spirit. There's a certain level 4 vine spell that's very handy when you get to the serpent temple... and just a short review of the short list of spells should identify the little gomer.

And I always train spell schools at the guilds (with the exception of level 1, and in rare circumstances, level 2). Spend all those skill points on sorcery instead.