Too many websites give long winded explanations of creating SSH keys for a password-less login, following all of the useless extra commands can be tedious but it's actually really simple.
In the end it boils down to;
Create ssh keys, if you've done this don't do it again
Copy to server you want to login to
Don't forget to check your permissions!
Permissions of .ssh should be 700
Permissions of .ssh/authorized_keys should be 0600