going with a kit makes it easy and guranteed done the right way.
i am not sure about the e36, but what i am doing with my e30, is i will get the e30 m3 springs and find shocks to match. (i will be looking at adjustables so i can better balance the car)
the springs are half the price of kits - modification will end up 3/4 inch lower and a tad bit stiffer.
do a little reserach on if the m3 springs in the e36 will give you the same effect.
other thing is
www.bavauto.com has a pretty easy way to pick out just the right suspension kit. ive seen it at other places too.