I vary the temp based upon the solder I am using and the kind of work. For lead-free solders, I use 850F, for some of the low-temp paste solders I use around 525F. Usually the solder mfr. has some kind of recommendation.
For copper-clad ties, I lightly sand the copper cladding with 800-grit sandpaper to remove oxidation, otherwise no matter what the temp, I end up overheating and the copper foil comes off before I can get a good joint. With clean work and good flux, the solder should apply easily.
Be careful about using higher temps on work with more mass. If you apply the heat for too long, you can still overheat the work. On flextrack, to avoid melting ties, I make heat sinks from small trips of paper towels that I wet with water from an eyedropper, then place/pack around the work with a fine tweezers. (They hiss as they heat up, but when they *stop* hissing, you know that the water has been driven off, and the temp of the protected part will then continue to rise.)
Also be sure to use a good flux (I use SuperSafe rosin-based) and clean the joints well when finished.
HTH,
Ed