The key to getting things done in Tonga is knowing how to find the right person. Tongans hate to say no, and if you ask someone to do something that isn't really their responsibility, they may give the impression of agreeing to do it, but in fact nothing will happen. If a Tongan breaks a promise, the best approach is to pretend to be grateful, even if they've inconvenienced you. Causing a Tongan to lose face is the worst thing you can do.
Tongans in official positions may seem sluggish and could keep you waiting while they chat with friends over the phone or read the paper. Just keep smiling and be patient: they'll notice that and will usually go out of their way to be helpful once they get around to you. Impatiently demanding service will have the opposite effect. (It's illegal to anger or threaten a civil servant or member of the nobility in Tonga.)
Both men and women appearing in public topless are punished with a fine. Of course, this doesn't apply to men at the beach. As in Victorian England, the Tongans usually go swimming fully dressed—most of them don't even have bathing suits. For a Tongan woman to appear in a halter top and miniskirt is almost unthinkable, and female travelers, too, will feel more accepted in skirts or long pants than in shorts. A woman in a bathing suit on a beach anywhere other than in front of a resort will attract unwelcome attention, and it would be prudent to keep a T-shirt on at all times and to cover your legs with a lavalava while out of the water. It's also considered bad form to kiss or even hold hands in public. (Despite all the strident public morality, in private, Tongans are often sexually permissive, and it's commonplace for married men to have affairs.)
Be careful with your gear in Tonga, as thefts occur all too often—don't tempt people by leaving valuables unattended. Even hotel rooms are unsafe. It's said that a Tongan will never buy anything if he thinks he can borrow or steal it. Thus, everything left unattended will be pilfered, especially if it's out where anyone could have taken it. This also applies to food left in the communal fridge at a guesthouse that also has Tongan guests, or the drinks on your table if you get up to dance at a disco. It's safe to invite one or two Tongans to your room or home, but with three or more things will disappear. Items left on the beach while you're swimming will have vanished by the time you come out of the water. Armed robbery, on the other hand, is almost unheard of.
Beware of Tongans bearing gifts—don't accept anything unless you're willing to pay for it. Often Tongan women and children will give unsuspecting tourists flowers, necklaces, or handicrafts with the sole intention of shaming them into paying money. When making purchases at shops or contracting services, pay attention to the price or you could easily be overcharged. The concept of "tourist price" is alive and well in Tonga.
Royal ownership of the land has led to several important differences with Samoa, where most land is village owned. Tonga's public beaches and roads tend to be dirtier than those in Samoa, largely because the responsibility for keeping such places clean is not felt by the local Tongan villagers. On the plus side (for visitors), there are usually no customary admission fees to swim off Tongan beaches or visit caves, waterfalls, etc, since the king isn't likely to be around to collect the money. In Samoan villages, such fees are routinely charged by locals who have an incentive to keep their property clean.
Dogs can be a nuisance in Tonga, chasing cyclists and barking through the night. They can be especially aggressive as you approach a private residence, but pretending to pick up a stone will usually be enough to scare them away. (Looking at it another way, you'll see some of the most wretched, abused dogs in the world in Tonga, and it's not surprising that they bite.)