My approach was to layout the control panel (buttons, joysticks, trackball, and spinner) on the raw particle board. Here you can see the rough markings and holes. This is a picture of the early stages of my second control panel. The pictures following this are of my original control panel (or my "prototype").

You have several button choices from Happs. Either the Competition or the Horizontal button will work just fine. These buttons require a 1 ¹/₈" hole. Trust me in that they just won't fit through a 1" hole!
 
As a general rule, I paint my control panel before mounting the rest of the harware. However, sometimes I add additional controls after the fact.

Here you can see what the back of the button looks like. This is a horizontal-style button. The microswitch will clip in the prongs. You'll notice that I didn't do a great job drilling the holes for the buttons. In the newer control panel I did a much better job. This original control panel was pine (bad choice), and splintered easily. CPv2 is made out of particle board.

The microswitch just pops in here.

And snap! You're done.
 
Now you just have to wire them all up. Notice the three prongs? One is a common prong, and you will always use it. The other two will be marked NO (Normally Open) and NC (Normally Closed). In MAME cabinets (and most other applications), you'll use the NO prong.