Good move, it dont matter so much if a joint fails on a fast jet, in my case it would be the catastrophic failure of my trailer lights
All about heat and a good tip. I was shocked by the difference a new iron and a bit of indoor working made!
Clean shiny wire ends, 1mm-2mm diameter flux cored solder, ensure copper wire gets hot enough for solder to flow. Have a clean solder bit on soldering iron, wipe off on paper if crusty or scrape carefully to remove black crud, until solder flows easily onto tip of iron. Dont sand the iron coating off the soldering iron bit or the copper core of the soldering iron bit will dissolve into the solder. Using old fashioned 60:40 tin/lead solder is much easier than lead-free. Sometimes need extra electronic flux from a flux pen with modern lead-free solder, also needs to be a fair bit hotter to melt the solder.. Never use plumbers acid flux.
I Well,, I can be a proper bad workman and blame me tools, me mate dropped around his soldering station , proper bit of kit, he is a retired RAF technitian, I have managed to glue it!!!
I used to think that I was crap at soldering too - mind you I was only 11 at the time and the soldering iron was my granddad's that you had to heat up on the gas ring.