- Pick up the correct end of the soldering iron
- Don't work with dangerous voltages
- Beware stored charge on capacitors
- Beware hot components
- Don't eat and solder (wash hands well before touching food)
- If anything smokes, don't inhale it.
- Watch for ends of wires you clip off. They can go in the most unfortunate places.
- Don't get things (especially hot things like solder) in your eyes.
1. yes, soldering iron may quickly cause burns.
though, FWIW, I have personally managed to more often burn myself worse with a glue-gun.
use caution if soldering around hot-glue, as the iron may also melt the hot glue, which may become very hot and sticky.
2. or, if you do, take precautions. for example, with things like 440 volt 3-phase, they will typically turn things off, and put locks on the switches to prevent them from being turned on while still being worked on. likewise, also caution is needed with residential AC power as well.
this is in strong contrast to being fairly casual with 12v or 24v, where the electricity is not felt if contact is made with dry skin, and usually only mildly unpleasant otherwise.
though, with low voltages, there is still a risk of accidentally shorting things if working with live power, which can be very bad depending on the power-source.
due caution is needed with lead-acid batteries (particularly larger ones such as marine batteries or things like automotive starter batteries), which can put out enough amperage to make things very bad if something shorts (wires can vaporize in a flash of light and heat, or components may explode and/or turn into tiny blow-torches, ...).
best idea is to make sure things work as-intended before hooking them up to such a power source (and make sure to use fuses).
so, when applicable, it is generally better IMO to test circuits on a current-limited supply (such as a lab power supply). a PC power supply may also be useable, as it will typically immediately disable itself in the case of a short or similar, but lacks adjustable voltages or controlled current-limiting.
also, it is easier to fix things if tested with a current-limited supply, as components and wires are more likely to survive. things are a little harder to fix if wires or components have exploded.
ADD: also be careful with lithium or LiON batteries or cells, as these pose a certain amount of an explosion risk (they may explode if overcharged or shorted).
comparably, NiMH and lead-acid batteries are a bit safer than LiON or LiPo batteries. there are tradeoffs, ex: NiMH has higher capacity and is more readily available for small cells, but is much more expensive than PbAc for larger batteries and has limited amperage (lead-acid UPS batteries are cheaper than larger NiMH battery packs).
3. yes. if working with capacitors, it may be a good idea to make sure they are discharged first.
4. also a burn risk, yep.
5 / 6. though these are more of long-term health risks, rather than an immediate danger.
avoiding smoke is a good idea though, as besides long-term risks, smoke from soldering can also make one feel sick after a few hours if too much is breathed.
soldering in an enclosed space can also be an issue, or in some cases, the smell of things like burning insulation or similar may linger for days (or, for example, making a board using magnet wire for traces, ones' working area may still smell of the stuff several days later).
burning plastic or components may also make for nasty smoke.
7. also, bits of metal go great in carpet...
