I always email with the hotel to re-confirm my booking. Print out the email confirmation and bring with me when I check-in. Always no problem encountered and quickly rectify the situation whenever I have the evidence on hand.
I always compare the same hotel with different online agent first. Agoda usually offers less "free cancellation" options for the same hotel, vs. booking.com has the option of free cancellation plus only ask for credit card guarantee only and then pay directly to the hotel. So I prefer booking or other agents who offer free cancellation for the same hotel of the similar prices.