These are some suggestions on building some skills. I haven't tried them all, but those I have work ingeniously. I've noticed that my lord never developed his iron body skill very well. It might have something to do with the fact that his AC was averaged at about 32 and that nothing could hit him.
One fight he was hit so badly and so frequently (hits that penetrated his armor and damaged) that iron body went up 2 points. Maybe if he was equipped only with the shield for protection that would help build both shield and iron body skills. A shield skill of 100 gives +4 AC bonus from shields, so his dragon kite gave +8 AC (+20 skill from shield). Maybe if I had him building these skills in a tougher monster area, it would also give my characters some reason to build their divinity skill (healing him after getting the crap beat out of him by monsters). Tip: don't depend upon regenerating stones and dulcimers of mending too much outside battle; it cost much divine skill in my party as it was (unless you're building engineering or music to 100). Use heal wounds, heal all or restoration outside of immediate battle instead when engineering/music reach 100.
Alternatively, it seems that my rogue and previous ninja gained stealth skill by being attacked by enemies... don't know for sure but I suspect this. From a previous game, this also worked with reflextion, but building iron body means that the character has to take melee damage. If I'm right, stealth and reflextion build simply by being attacked in melee. Perhaps to keep from killing the enemy too quickly, the characters could equip *weak* weapons, and use the fight experience to have the spellcasters develop their weapon skills and divine magic. Just be sure they can win the fight.
A way to build music skill:
find the Viola d'amore in He'li's inn. Initiate dialogue with any NPC, keep using the Viola on them until the bard falls unconsciouss. Wait for bard to regain stamina. Repeat as desired; it works for me (slowly). Female bards can use lockets of reflection (stamina regen) to significantly reduce downtime.
A foolproof way to build iron will:
In lower marten's bluff, there will be t'rang guarding a door in the corridors behind Z'ant. In one my recent game, the guards moved somewhere else after I finished a later T'rang assignment, leaving me able to open the door. It requires the correct three eight digit number to open. Just enter any combination but this one (the preset one works). Every time you try to open the door and the combination is incorrect, the door will cast freeze flesh on your party. I used this to get both bishop's iron will up to about 96 before I got bored with it. You can click on the door button all you want, but the game may slow somewhat from processing the graphics of several spell castings at once. Remember that you open the door (and walk through) at your own risk...
I read on another forum that it's possible to build earth and mental magics by casting low to mid-level divine trap and knock knock on heavily locked doors and chests (at least six tumblers). I haven't tried it yet but it sounds promising.
Anyone who wants to add to this list or correct any errors within is encouraged to do so.