My typical setup for a development box in VirtualBox uses two NICs. The first uses NAT to allow the box to communicate with the outside world through my host computer’s network connection. (NAT is the default, so shouldn't require any setup.) The second is a "host-only" connection that allows my host and guest to interact.
To create a host-only connection in VirtualBox, start by opening the preferences in VirtualBox. Go to the "Network" tab, and addd a Host-only Network. Modify the host-only network, and disable DHCP. Make a note of the IP address. (Feel free to set the IP address as well, if you like.)
Next, assign this host-only adapter to the virtual machine. Select the VM and press "Settings". Go to the "Network" tab, and select "Adpater 2". Enable the adapter, set it to a "Host-only Adapter", and select the adpater you created above.