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
ssh-keygen
Copy to server you want to login to
ssh-copy-id user@server
Don't forget to check your permissions!
Permissions of .ssh should be 700
Permissions of .ssh/authorized_keys should be 0600