Try using a hemostat or some other heat sink between the area of the component being soldered and the component itself. Do not use acid core solder on electronics; use rosin core solder. The small rolls of solder that are used in electronics today are a tin/silver mix with a rosin core. The area being soldered needs to be clean with no oil or crud on its surface. Alcohol can clean this, with a Q-tip if appropriate. Or brake cleaner on a Q-tip if necessary. Then the gun tip needs to be clean and tinned. To clean a tip, heat turn on the gun and heat the tip till it smokes (a sign it is dirty, clean tips don't smoke). Wipe it off while hot with an old clean rag, t-shirt or towel. Then let it cool, then clean it with some fine grit sandpaper or emery paper. Wipe it off. Then heat it till it is hot and apply solder to it, all over the tip, then wipe it off while hot. Now you should have a nice clean silvery tip on your gun and it is ready to use.
Heating the gun till it is hot will not hurt the gun; it is made to be heated.