It's nearly impossible to find two free seats together in Business or First Class, so if you're travelling with a partner, your chances of both getting upgraded are nearly impossible. However, finding a single seat (it's usually the least-desirable of the premium seats, near the bathroom and without an overhead locker) is a lot more doable. If you fly solo, it's far, far easier to get an upgrade.
Sweet talk
Sweet talk means more than just being cordial and giving compliments at the check-in desk. You can try to elicit pity with your sweet talk at the airport (or on the phone to the airline prior to the flight), which, if successful, will work sympathetically for your upgrade potential. If there's a particular reason you're flying somewhere - a funeral is ideal - use this to your advantage. Likewise, if you've been unexpectedly separated from your travelling party, or you're travelling alone because your spouse could not make the trip with you, throw these into your sweet talk with airline staff. They need a reason to upgrade you over the others who want the same plush seat.
Book off-peak, unpopular flights
There will usually never be any spare premium-class seats on weekend flights (particularly Sunday arrivals), during school holidays, and busy times of the year like Christmas. However, unpopular flights (such as those that arrive Tuesday to Thursday, those with connections in undesirable locations, etc.) are more likely to have business or First Class seats to give away. Think about this when booking your fare in the first instance.
Book flexi fares
If you've booked the cheapest possible economy ticket, it's difficult to get upgraded. However, if you have already forked out for a fully flexible fare with an excess baggage allowance and the rest of the works, it sends a message to airline staff: "I'm not a cheapskate". Such a notion works in your favour when the only extra benefit you'll receive (that you haven't already paid for) is a larger seat in a different part of the plane.
Be early at the airport
The last time I was upgraded, I was at the airport four hours before my flight. I simply asked if there was a seat in Business Class available, because I had a recognition upgrade owing but it hadn't been confirmed. I was informed there was one seat but it hadn't "opened up" yet. When it did become "available" (i.e. nobody had booked a last-minute Business Class fare in the hours before departure), my name was already at the top of the list because I was physically there first.
Make friends in high places
The airline staff that work in the frequent flyer lounges, not those who work out in the general check-in area, are the most likely to upgrade you. Befriend these people - ideally when you are not seeking upgrades - so when the time comes to ask for one, you already have a casual relationship to work with. Also, look out for the most senior person behind the desk (in job rank, not in age). They are the best friends to have. Being mates with those who work in airlines' corporate divisions can help, too.
Help out on a flight
If you give medical attention to another passenger on a flight, assist in the comfort of an elderly or infirm passenger by moving to another seat, offer to be bumped to another flight because of overbooking, or help out an airline in any other way, chances are that airline will log a free upgrade for you next time. As noted with all other tips on getting upgraded to Business Class on an airplane, it pays off if you're a good person.
Join the conversation on the Herald Life Facebook page