The very first step of making a CNC is PLANS! I got plans and hardware kit from buildyourcnc.com
which came with measurements for the CNC and all the nuts and bolts you need, besides the lead screws and various other parts. After I got the measurements of the CNC, I designed it on Google SketchUp as well as a stand for it and a computer to operate it. After I had a set design, I began building it. First, I made the CNC part of it and then I made the stand to fit. I used MDF for the CNC and 2x4s and 1/4" plywood for the stand. I also casters on the stand so I could move it around with ease.
Here you can see time lapse videos of me assembling the CNC and stand: