set the metronome to the tempo you want to play at (like 120 bpm or something) then just practice playing in time. if you have riff or someting, or a piece that you want to plya, play that to the metronome. its just to keep time. like a drummer. or you can practice scale or excercieses with it. anything you want. mess with it.
as far as palm muting, some bassists do, some don't. they are usefual occasionally. up to you really.