i think that might be a really broad question...
without going into detail about how IK works i didn't think there was much to know
create an IK chain, move the effector and all parent bones moves accordingly with constraints.
you can add constraints to joints so they don't translate or rotate past a certain value
such things are found in the Maya tutorials that come with the program involving a robotic arm picking up a box and putting is down somewhere
if you look at other people's work where they have a character rigged to some deformer you'll see they have attached a whole lot of circles and other various wire shapes. these shapes are used to easily select the effectors or other deformers instead of you having to fiddle with visibility of certain objects to get to your deformer
(i wish i knew that earlier...it's not cool having to turn on joint visibility or toggle x-ray mode... it's not something covered in the Maya tutorials and i didn't know about it until i played with XSI)
that's a "Ch" pronounced as a "K"
Computer skills I should have:
Maya, XSI, Photoshop, AfterEffects, Motion, Illustrator, Flash, Swift3D