firstly the honeymoon one rarely works if you are going to a honeymoon destination, like mauritius... A friend in the industry told me that on one flight they had something like 47 newly married couples! She also advised that a lot of airline now have their staff justify why people were upgraded, in case family of crew are being giving preferential treatment....
I once got upgraded economy to business, after being delayed at check in for nearly an hour... a family ahead didn't bring any passports, and by the time it was sorted we have 15 min to get to the gate! All 8 of us who got trapped behind this family got upgraded.... But not a route i'd recommend, as it was really looking like we wouldn't make the flight at all... But well worth it for a night time 8 hour flight.... nice space to relax and sleep!
I think best recommendation is join the frequent flyer club for the airline, check in early, be pleasant to the check in staff, you might not get the upgrade but might get the nice exit seat with extra leg room.