What points amount are you aiming at? As a starter, I'd recommend 1000, but the game only gets really fun (and more balanced, generally speaking) at 1500-2000 points.
For Isengard, the things to have are Saruman (even if he's a quarter of your points), Thrydan (a captain, but with 2 major bonuses for free), Uruks with Shields (great front line troops), Crossbows (death from a distance to nearly anything that isn't very well armoured), and some elites you like (Berserkers, Ferals, Dunlendings, whatever. The possibilities are endless.)
I've made a full review of Isengard units, tactics and relative values here:
http://one-ring.co.uk/viewtopic.php?f=88&t=22651.
But to really help, we'd need an army list or at least some idea of what and how much you want.
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"... Telchar wrought it in the deeps of time."
-On Andùril, The Lord of the Rings