In the electronic work the adhesion quality of the solder is controlled by pushing the solder to the heated base.
But in modeling you better chop a little solder from the wire for the iron tip to control the quantity of solder.
Therefore as first step you should chop the solder finely.
To solder parts well, you should keep the iron tip shiny.
If the iron tip is rusty you file away the rust with a paper file, apply flux and cover it with solder.
While you work rub the tip against the wet sponge to remove oxidized solder.
At first, you apply the flux to the part to solder with a worn-out brush or toothpic.
Next, you catch a little solder with the tip of the hot soldering iron.
At this time, If the solder becomes spherical and you can not apply it on the tip the tip is oxidized. You need rub the tip against the wet sponge and remove the oxidized solder.
You hold the tip to the part where the flux was applied and heat it. When the part is enough heated, the solder should flow from the tip
When you have finished soldering, wash the part in water to get rid of the flux.
Then you are done.
When you solder slightly larger part and board-shaped part, you should presolder it.
To presolder a part, you should do it repeatedly and heat from the top.
When the plated solder of the lower part melts by heat and shines, It is the sign that soldering is completed.
When you are soldering a part where you cannot point the tip to directly, you should spread solder by heating from the circumference of the part to solder.
You apply a flux to a part to solder, ride a small chopped solder and heat from circumference