If you'd like some vim-like bindings in tmux, you can turn on vi mode. To do
so, add the following line to your .tmux.conf file:
setw -g mode-keys vi
With this added and tmux re-sourced, you'll now have a variety of vi-like
bindings. For instance, when in tmux's copy mode, you can now use v to
begin making a visual selection and y to yank that selection into tmux's
copy buffer.