You can change your home in NetInfo, which will also change your startup directory in the terminal.
Alternately, you can add a cd command to your .*cshrc file or .bashrc file, whichever is applicable to your configuration.
For instance, to default to the root level of your boot hard disk:
echo "cd /" >> ~/.cshrc
Or you can add it manually to the applicable shell initialization file with a text editor of your choice.