I use tmux a lot for handling different sessions. What is annoying that everytime when I ssh to a machine a first need to run the command to open the tmux session.
Here is a simple config so that when you login into ssh it will immediately run the tmux command so that you don't have to type it yourself after login. Saves you a couple of seconds with every login :)
$HOME/.ssh/config and add the "remotecommand" for the host that you are loggin into:
AddKeysToAgent yes Host myspecialhost.nl RemoteCommand /opt/local/bin/tmux new -A -s chat
Now do a
ssh firstname.lastname@example.org it will do the command.