There are times when working around your home that you need to repair or build something electrical and selecting the right soldering iron will make the difference between having a really easy time getting it right and causing more damage than already occurred.
The first thing you should understand about Soldering is that you are not welding the wires or components together. You are attaching them with a metal that has a low melting point.
To apply solder you need the wires or component clean of any oxidation. Oxidation on steel is easy to spot because it looks like rust. Oxidation on other metals like copper normally keeps the same color but looks dull. You need to clean that oxidation off so the wire or component end you want to solder is bright and shiny.
Once the component is clean you need to use a flux to prepare it for soldering. Flux if acid based will also clean while you solder but you should only use Acid based products if you are working on Plumbing and not on Electrical or computer components because no matter how hard you try you can not get all of the acid off after you are done and it will cause damage over time.
Flux normally comes in a paste that you apply with a brush but it is also available in a liquid and if you are soldering small components like computer or radio equipment you should buy solder that has a center core of flux.
When you are preparing your soldering iron you want to clean the tip off and then apply flux to the tip. You can then tin the tip with solder. Tinning is when you cover the end of a wire or in this case the soldering iron tip with a thin coating of solder that will aid in the quick transfer of heat.
You can actually buy components like small LED lights that are tinned from the factory on the end and they make life really simple because you don’t need to clean and flux them you simply apply enough extra solder to complete the connection. Pre-Tinning your wires or components also means you won’t use as much heat and this will reduce the chance of destroying a motherboard or frying insulation on a wire while you try to complete the connection.
Ok so we went over the basic steps of soldering and if you didn’t know its slightly more complex than just forcing solder onto a wire or component.
Heat is a big factor. If you heat something like a LED Light Leg too much you could destroy the LED Light or at least reduce its life. Doing things right will make your work better. Clean and pre-tin when you can. Apply flux where you want the solder to flow and not to any other areas and the solder will stay in the fluxed area pretty much.
However working on motherboards or soldering wires is only part of the reason you might want a soldering iron. There are many crafts like Stained Glass Making and repair that also require a special soldering iron.
You should know the differences and only use the right soldering iron for the right job.
Selecting the right Soldering Iron
As mentioned above the correct soldering iron will make life easier and so will preparing your work before you begin.
The actual time to solder a wire or a capacitor to a motherboard is only a matter of a second or two. All the other work is what makes it happen that fast. If you find you are fighting your work to accept the solder then your preparation is lacking. Stop and review before you cause damage.
Soldering irons come in three basic types.
Utility or Craft Soldering Irons should only be used for art projects. The temperature range on these tools is practically impossible to control but they give you a wide tip for making repairs on Stained Glass or completing other work quickly. You would never want to use detail soldering iron to complete this work as you would not have enough heat and the results would be poor.
The second type of soldering iron is a Soldering Gun. They actually have the shape of a gun and allow you to attach a few different types of soldering tips for general work. They can be used in a pinch for most projects but I would not suggest them for fine detail work on motherboards or other circuit boards because the control of heat is not that good. Normally there are only two settings. Hot and really hot.
The final type of soldering Iron is a Detail or Electronics Soldering Iron. If you work with a lot of electrical equipment then you really need to buy this type of soldering iron. If you can find one cheap .. maybe on discount or used you should pick one up no matter who you are so 
you have a soldering iron that has good control. Normally they come with a number of small tips under 1/4″ and down to a fine point. The Chisel design tip that is about 1/8″ wide or smaller is what you use for electronics equipment like soldering on a component to a motherboard. The best models come with a digital heat reading and a full rheostat type dial. The next models down might have 10 settings for heat range and the final ones that some companies try to sell as electronics soldering irons do not have adjustment and should be considered craft soldering irons not electronics soldering irons. You could still use a non adjustable type for soldering larger wires possibly.
Final Note
As we talked about preparing your work is 95% of the job the rest is picking the right products like acid free flux or solder with a flux core. Finally soldering should only take an instant or two.
If you find you are fighting to get wires tinned or soldered together they probably aren’t clean. Many manufacturers use liquid to protect from corrosion you will need to remove that or use a different wire.
Repairing Electronics like a Radio or even a computer board is not as difficult as you might think. Things like capacitor Barrels that pop normally have markings. You can buy replacements for a few cents or a few dollars and save your electronics and your money if you replace them.
Soldering of electrical wires inside your home .. meaning the ones in the walls of your house is not safe. Home Wiring should always use mechanical connections like wire nuts or crimp connections.
Wiring in your vehicle is normally completed with crimp connectors not soldering. However there are times when you may need a soldering iron to repair things in your car.
Electronics are sensitive to heat so you want to use just enough heat to melt the solder and not overheat the motherboard or components. Once the connection is completed cool it quickly with a moist qtip or paper towel but never put it back in service until you have dried it completely. Its better to leave it overnight if you doubt if its moisture free.