It is always sensible to remember that although the pilot is in 'control', the stoker provides an invaluable service.
Simple rules make life easier. For instance, the pilot always has feet down first, up last, the pilot warns the stoker when unavoidable bumps are about to be encountered, the pilot communicates for launch, stop and for changes to pedaling.
For instance, we start by the pilot straddling and holding the machine whilst the stoker mounts and sits with feet on/in pedals. The pedals are positioned for best launch for the pilot and to launch there are a series of instructions that we use:
Pilot: Ready to roll? Telling stoker that we are about to move off.
Stoker: Ready. Only when soter is ready. If they are not ready they should say so.
Pilot: Rolling. Pilot launches.
It is important for the stoker to respond to the pilot's pedalling and not drag or pedal through. It's much easier than it sounds.
For your first few launches you might have comedy wobbles. This is caused by the pilot over-compensating and / or either stoker or pilot giving it too much ooomph.
The pilot should talk to tall the time telling them when they need to indicate to turn left or right, to stop pedaling, to ease off, to beware of bumps, and when slowing or stopping.
When bringing the machine to a halt, the pilot should have both feet on the ground and a firm grip on the machine before the stoker attempts to leave the bike.
Fit bars / pedals / saddles that you both prefer wherever possible. The experience should be a good one.
Golden rules: (IMHO)
Pilot is first on, last off.
Stoker keeps feet off the ground at all times when on the machine unless specifically requested otherwise by the pilot.
Stoker resists squirming about when on the move.
Stoker responds to pilot's pedal rhythm, cadence etc. where possible.
Stoker says if they need the gear changing.
A tandem generally has a larger turning circle than a solo and generally will take longer to haul to a stop.
Sounds really boring, no? It's not. You'll get used to riding a tandem and it will become second nature just like riding a solo or a bent. You will have heaps of awesome fun and be the object of desire and wonderment of young children and old adults alike. So, don't forget the big grins.
Of course, the stoker, if of the intimately friendly variety, can administer fondling of the pilot at their own discretion. This piece of information comes with a cyclists health warning as such actions can cause distraction to the pilot.