Dale says:

You could get by with the cheapest soldering iron you can find…but don’t. Soldering fine wires to small circuit boards takes a minimal amount of heat but soldering feeder wires to a heavy bus wire takes more. Your best bet is to look for one with a holder on a heavy base, with an on/off switch, and with a rheostat so you can adjust the heat output.

I won’t recommend a particular brand but you should look to spend between $30 – $50USD.

vobbec says:

I have two soldering irons, a 15 watt one with a fine tip for soldering to DCC decoders and a 35 watt one with a larger tip for soldering feeder wires to the track. Make sure the parts you are soldering are clean and use flux for best results.

Stewart says:

Two irons are best, Minimum 15watt for PC board / small work, large iron for heavy duty 35 watt min,

The tips are important and need caring for as they do the work, with new irons always Tin them first, this helps solder to run better, easy way is wrap an inch and half of solder around the tip (making a spring shape) then switch the iron and allow the solder to melt, job done.

Flux paste should always be used,

A Sponge pad kept moist is a must, used to wipe the tip during soldering operations, Helps keep the tip clean.

Less is more as the saying goes with solder, it dose not require a large amount to make a good joint. I would suggest practice to get used to seeing the solder melt and run before attempting attaching droppers etc, and pc board work

Good luck