Give some thought to the layout of your components. If you do it right, you can minimize the mass of wiring in the final result.

A schematic is shown on the right. The capacitors C1 are 0.1µF ceramic, and C2 is a 47µF tantalum. All capacitors are probably optional, but they lower the noise level slightly.

Note that any unused pins on the XBee should be left unconnected. Really. I initially had all unused analog inputs grounded, and the XBee was unhappy about that.

Assembly is not particularly difficult, since all the tiny surface-mount stuff  is on breakout boards already.