Milling technique question, doing two sides?

Howdy,

I have some pretty basic questions about machining techniques. If
someone could direct me to a good resource for these kinds of things I'd
appreciate it.

I'll be working with a Taig mill without a rotary table (for now :) ),
and I'd like to be able to machine some two-sided items. As an example,
something like the shell to a calculator or other small electronic
device. Two pieces that require milling on front and back. After doing
the first side, how do you turn the material over to do the other side
and get it positioned precisely?

Thanks,
CS