In my Emacs environment. I am using helm-mini to work with buffers because The advantages of using helm-mini, you can see the all information of helm-source-recentf, helm-source-buffers-list, helm-source-buffer-not-found together in 1 helm-buffer.
After changing computer Ubuntu to Mac OS, few keyboard behaviors are changed in Emacs. One of that is choosing buffers while visualizing them. For me, It is necessary to see buffer what I am going to select. Helm gives us chance to visualize buffer by pressing C-z or C-j but as you know these are not effective. So I changed default behaviors of C-Arrow-keys to visualize and go next line.
(define-key helm-map (kbd "<next>") 'VisualizeandGoNextBuffer) # Control-up
(define-key helm-map (kbd "<prior>") 'VisualizeandGoPreviousBuffer) # Control-down
(defun 'VisualizeandGoNextBuffer ()
"Helm visualize and select next buffer."
(defun 'VisualizeandGoPreviousBuffer ()
"Helm visualize and select previous buffer."
Also, you can use that shortcuts with other helm functions.