So, this is the first time I've played the game. I haven't trained as a mage yet, but I created stats favorable to that class. I have just leveled to 6, and don't want to level again until I have trained in the Art. Can I get to a trainer without forcing the main storyline? I have also just added Dakkon (or however it's spelled) to my party, so I guess my points are going to be fewer in between than previously, but still...

You can find trainers for fighter, thief and mage as soon as you're out of the Mortuary.
Explore Sigil, talk to everybody and you will eventually find them.

Tell us if you'd like more specific hints ;)

No, I wasn't asking for spoilers. I was trying to avoid that. Before I started the game, I read up on the basics of gameplay and whatnot. One of the points I noticed was that You get a class boost at level 7 and then another at a higher, but that this effect is only cumulative if you meet it in a single class. So I assumed that it would be better to train as a mage before leveling to 7 as a fighter, I had just leveled to 6 as such. But I was far too hasty in coming to this forum, as I found a mage trainer in the usual spot that one will fin her when playing this game. I thank you for your reserve in answering this question. I happened upon the PC that could help me once I set that as my main goal. I simply didn't complete any more assigned quests until I had trained as a mage first. Thank you.