1) Maximize your CH and your Persuasion skill. Purchase expertise in Persuasion to give you the most possible followers: six, not counting free followers such as familiars and Dog. Having a 20 CH (charisma) means that no one will leave you or refuse to join you, despite issues with your alignment or with any of your other followers.
2) Mental spells are your friends. Just remember that when they wear off, there will be a backlash; if the backlash is enough to drop their relationship with you down to Hatred, prepare to be attacked. Stun will also buy your followers some time to protect you, if you're being attacked.
3) Other helpful spells include Purity of Water (+4 to Beauty, stacks with itself), Shield of Protection, Minor Healing, Teleportation, and the Nature college. The more spells you have, the higher your MA, which makes scalable spells like Minor Healing that much more effective.
4) Give your followers the best weapons and armor you can afford. They're your enforcers; don't gimp them. Be sure to match magic to magic and tech to tech; giving a mage a gun is a BAD IDEA.
5) If you're not planning to fight, then real time mode may be your best bet. You can use the space bar to toggle turn-based if you need the time to cast a spell or two.
6) Invest in DX (dexterity) as well. Higher DX means more APs (action points) which equals more time to do stuff, especially in turn-based. Similarly, a higher CN (constitution) means faster Fatigue recovery and less need for FT potions.
7) IN (intelligence) is mostly a waste, unless you're investing in tech colleges. Minor Healing is much more practical than the Heal skill, unless you're dealing with high-TA characters; and even then, there are salves galore that can be purchased or found. Gambling (the other skill that requires IN) is by its very nature unreliable and unnecessary. The only way IN helps mages is by allowing more spells to be maintained at once (two at IN 8, three at 12, etc.)
8) Might as well invest in Haggle; it requires WP (willpower) but puts your CH to good use. With expertise, you can sell anything to anyone, and buy at much lower prices than otherwise.
9) Minor spoiler: There is one point (in the late middle game) at which Virgil leaves you; if you've given him anything especially valuable, reclaim it before he does so, since when you find him again he'll be starting over with nothing.
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SPOILER
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∞) There is a way to take over the whole world, one by one, with a broken spell exploit. No details here; google "meta abuse" if and when you wish to give it a try.
Post edited April 29, 2015 by TwoHandedSword