In VirtualBox Manager
Is Settings > Network > Adaptor 2 set to Host-Only Adaptor (vboxnet0)?
Is Settings > System > Enable I/O APIC checked?
In the VM
Is OpenSSH installed? ($ sudo apt-get install openssh-server )
Have you made the changes to /etc/network/interfaces, replacing eth1 with your interface name from ifconfig ?
Have you brought up the adaptor with $ sudo ifup <interface name>?
On your host
Have you determined the correct IP address to ssh into? (Runifconfig. Use the value of vboxnet0's inet field. If vboxnet0 is not available, review the section above In VirtualBox Manager)
Run ssh <username>@<ip address> and log in.