I'm an SC'er and let me provide some advice
1)Let an SC'er build your template for you. Some will charge you for that, some won't. It's worth paying if you have to because most people mess it up.
2)Find all the jewelry/accessories that you can to maximize your Dexterity, Piety, and your skills.
3)Steer clear of asking for +Power on your armor. It is very expensive (imbue point wise) and since you only get +26 at lvl 50, it's hardly worth it.
4)Be selective about your resists. Think about what resists you REALLY need. Like +power, +resist gets VERY high imbue point costs as you increase from 3 to 5 to 7 to 9. For a caster, I generally recommend Energy and Spirit (mezzes) and Thrust (Stealthers) resists maxed and whatever else you routinely run into.
5)If you've got 99+ quality armor, think about having the SC'er overcharge (OC) the items. You can reliably get +4 OC on 99's and +5 on 100% (MP) items. Be warned, though, that this can be VERY expensive if you have gems that are fairly high level.