Miller Indices (Solid State Physics)

How to find millerindices:

1) Choose origo in some arbitrary point.

2) Choose a plane that DOES NOT intersect origo. Find the intersection in the x-axis and the y-axis. Lets say (1,2).

3) Invert (1,0.5)

4) Extend so that you get integers (2,1)

Your millierindices are then (h, k)= (2,1)

Im not so god at it. I only know how it works on a simple basis. The point with millerindices i think are that if you choose a "miller-plane" (h,k,l) then if that intersects origo, then the plane intersects x-axis at a/h, y-axis at a/k and the z-axis at a/l. a is the width of the cubic structure.