Homebrew PCBs

Hello,

I'm designing a VERY small board (less than 1 square inch) and there 
is an analog part and a digital part.  The board is going to be two 
sided and I plan to use surface mount technology and mount everything 
on the top side with a ground plane on the top side and route all 
signal lines on the botton side.  I'm going to seperate the analog and 
Digital ground planes but my basic question is how?  Should there be a 
common area in which you must go through a 180 degree bend to get to 
it from each side.  Will that block out most interference signals. Or 
should they be seperated completly except through ferrite beads?  
Also, is it a good idea to route my signal lines through the common 
ground plane that "S"'s it's way through to the other ground plane.  
Any help is appreciated.

Jimbo