Some metallic threads are more brittle than others. I suggest on top of using a metallic needle (or topstitch in a pinch) that you slow your speed down to prevent shredding. I really hate when that happens. Really thick threads will probably have to be used in the bobbin (called bobbin work) and you'll need to adjust your bobbin tension. I have a separate case for that (I have no idea what to do if you have a drop-in bobbin). I have never used metallic in the bobbin and the needle at the same time so can't help you there. I guess that is an experiment I'm going to have to try.
Monofilament thread is kind of curly (again depends on the brand). I find using a vertical holder works best for me (sometimes I'll use one completely off the machine to "stretch" the kinks out). I think there are better brands than others.