Tip #2: Many times, a hotel or hostel in a foreign country will ask you to pay a deposit when you check in and pay the rest when you check out. In order to reduce the amount of foreign coins you bring back home with you and have to lug around (they get HEAVY), consider paying for your lodging using these coins.
A couple of summers ago, I traveled around China, Macau, Hong Kong and Thailand. By the time I was on my way back to the States, I had accumulated way too many coins and didn’t think to use them during my travels. Yes, I wanted a couple as souvenirs but they added extra weight to my pack and once I got back home and counted them all out, they added up to $35USD! That was money I could have spent on more curry or sightseeing, had I used them during my trip or put back into my bank account had I exchanged them at the airport.