Hand soldering SMD 1206 components
You will likely find that 1206 are actually quite easy to hand solder. When you get used to SMD boards, you will find they are actually quite large.
With a standard iron, I find it quite simple to hand solder 0603 components, and with a small precision iron, 0402 can be done.
Your best bet and my recommendation if you haven't don't it before is to pre-solder one of the pads, then heat up the solder with your iron, and place the component with tweezers. Once you are happy with the position, remove the iron then simply solder the other side. This is by far the best way if you aren't sure about your soldering skills.
If you have access to some flux, then make sure to use it!
If you want, you can make a PCB with a few different footprints on it, have a few 1206, a few 0805, some 0603 and so on, and use it as a 'practise board'. This way, you can develop your SMD soldering skills, and when you get more confident, you can switch to making PCBs with 0805 or 0603 components, as the larger sizes are getting harder to come by!
After @pipe pointed out the link in the question, I don't really have much to say on it. I have never ended up with a cracked capacitor or any component. The article seems to be talking about the heat shock of the component, and cracks occuring during the rapid heating and cooling of the component and the solder. By only soldering one side at a time, that should reduce these stresses anyway, the article seems to point to both sides being soldered very quickly, or at the same time. It also mentions that is can cause failures during a "board bending resistance test" which I assume is not needed in your application! So really, I wouldn't worry too much about it. If you do find on the off chance you have a broken capacitor, just replace it!
I hate to contradict Murata; they are a solid company with good products and helpful documentation. However, I've been hand-soldering MLCC's for a decade and have never had a known MLCC failure. I don't preheat the board or components, and I'm not more careful with MLCCs than I am with any other SMD components.
I generally use a Weller WES51 soldering iron with an 0.031" conical tip. I've probably soldered a thousand components from 1206 (these are huge) to 0201 (I need a magnifier for these). Sizes down to 0603 are basic. 0402 is a pain. I'll only hand-solder 0201's if I have a really good reason :) These are imperial units.
Here's my technique, which seems to differ from others I see here. It's not necessarily better, but it works for me:
Apply a small amount of solder to one of the two pads. Remove the iron.
If I have a lot of components to solder, I usually prepare each location (one pad per component) in one pass. More time efficient :)
Place a component on the pads. It will be resting with one connection on the lump of solder, and the other connection on a clean pad.
Hold down the component with a toothpick.
Touch the iron to the lump of solder. When it melts, the component will sink down to the level of the board. Remove the iron, then the toothpick.
Note that this isn't a good solder joint yet! It just holds the component in place.
I do this with each component before proceeding.
Now that they're all tacked in place, I solder all of the unsoldered edges. This is straightforward; just use the iron and solder wire.
Finally, I go back and retouch all of the original edges. This is critical, as some of them may have cold solder joints. Either add flux or just add a little more solder (for its flux).
So, basically, I tack them into place, then solder the other side, and then resolder the first side. It doesn't take long!
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.