Homebrew PCBs

I read some articles about this problem and all talk about star 
groundind, but nothing about power supply line.
Let's supose we have a simple transformer-bridge-cap-regulator power 
supply and two circuits, one analog and one digital. What is the best 
layout in this case. I mean, what is the principle? A longer power 
line and a shorter ground line for the digital section? It's OK to 
connect the digital power line at the same single point whith analog 
and the digital ground between transformer and bridge. 
Or simply two ground and two power lines conected at the power supply 
entry, after the filter cap? 

Adrian