1206 (Imperial, 3216 metric) is very easy to solder by hand.
It's very big in the SMD world.
With an normal, 0.5-1mm chisel, iron you can go down to 0603 (imperial, 1608 metric), then hot-air becomes a requirement to do it with reasonable quality.
The need for optical assistance depends on the operator.
Soldering with an iron is easy with these 3 steps.
1. Tin one pad, the other one must be clear.
2. Place component with tweezers while the pad is molten by the iron.
3. Solder other pad, this is where you need thin solder.
It is essential that you own at least lower or equal than 0.5mm solder with flux core. It is also important that the iron is not too hot, so you have some seconds before the flux is gone.
If you're pulling solder away with the iron (little spikes), you're out of flux. Add more.
It might work poorly with leadfree solder, add more paste flux in that case. (eg: SMD291)
With hot air, just tin both pads, add flux paste, drop component, and heat it. It will literally "flop" into place.
You can never add too much flux. Although it might smoke a bit. Just clean it afterwards and don't breathe the smoke.
Note that above method of soldering is not the recommended method by the manufacturer. It violates the thermal profile recommendations of the manufacturer, and might introduce physical stress on the parts due to uneven heating. This might not give you any failed parts immediately, but it might reduce the MTBF, and in the long term, or high volume, you may see higher failure rates then when correctly reflowed. Basically you work out of spec.
It's just like ESD, you may never observe cause and effect directly, but it's definitely a factor.
If your intention is to do this professionally, please invest in a hot-air station. It's worth it.
One trick when soldering with hot air is to use the surface tension of tin, it's amazing and does all the hard work for you.