Just one more thing - if there is significant precipitation when about to do the walkround, then make sure you send student to do same or if you are working for an Air Transport Undertaking get the First Officer to do same (assuming you are Captain!!).
Seriously though I agree 120% with DB6 - do as the checklist says. However I have some reservations about "sharing" the walkround (which incidentally in the UK is a Check "A") - remember that as the commander you are responsible. I am not saying I would never share the walkround but it all depends on the situation.