Problem: Unable to SSH into a digitalocean droplet due to error, "Access denied (publickey)"
1. Login as root to your server via digitalocean's console utility
2. Edit the contents of /etc/ssh/sshd_config (eg. nano /etc/ssh/sshd_config)
3. Find and change the value next to PasswordAuthentication from no to yes, and remove any preceding pound sign (#)
4. Save the file and then reload the SSH service (service sshd reload)
5. Run the following from your LOCAL device: ssh-copy-id user@ipaddress
6. Change PasswordAuthentication back to no if you don't want to be prompted for a password when you login (and don't forget to reload the service)
Note: The ssh-copy-id command assumes your keys are located in ~/.ssh and named exactly id_rsa.pub - otherwise use: ssh-copy-id -i /dir/mykey user@ipaddress