While soldering may seem intimidating for beginners, it is really simple and straightforward.
I would suggest to try soldering on some spare wires first. Then do a small handwired project like my budget macropad: you cannot really mess up anything with a handwired project. PCB and SMD soldering is another case (parts and the PCB itself can be ruined), but don't worry about this yet.
Soldering through hole stuff is pretty undemanding. You need a soldering iron with a pointy tip and that's it. The iron shouldn't be too bulky, but anyway, almost any iron will do the job. You don't need much power or fancy features like temperature presets, auto-sleep function etc. You can buy a cheap iron until you're sure you like this hobby.
Solder wireI use 0.8 mm diameter solder wire. Anything about 0.6-1 mm would probably work just perfectly. Avoid cheap stuff from aliexpress though: they stink, resin bubbles exploding all the time. Buy your solder wire in a local shop instead. The general store I usually go to sells only one type, it's a local/noname brand. I bought 100g for about 6$ and this amount will last me for several keyboards, probably dozens of them.
TemperatureI use my iron at about 340°C. I've set this at the very beginning and don't bother with it. It would probably work the same at 360 or 320. If you cannot set the exact temperature on your iron, you can still compensate with how long you hold the tip to the joint. If the solder material melts instantly (probably too hot iron), you hold the tip for a shorter time.
Protective measuresKeep your desk tidy. Avoid sudden moves. Try not to burn yourself or stuff around you. Wear protective glasses. For longer sessions room ventilation is important (open the window and/or you can place a fan on the desk).
- Practice on spare wires.
- You may prepare your contact points with some resin. (The more weird the joint, the more this helps.) Simply put some (very little) flux/resin on the points/wire ends/diode leg etc. to be joint.
- Turn on your iron.
- Once your iron is heated, put some solder on its tip by touching the solder wire.
- Touch the iron to the wire for a short time: you heat the contact points and the fluid solder material flows to the contacts. Remove the tip from the contacts and the solder material becomes solid.
- Clean your tip on that brass sponge/ball thing. (I find using wet sponge barbaric.)
- Turn off your iron.
- Wash your hands because of the leaded stuff.
Great! Now you know how to solder. Grab your iron and start your first keyboard project.