when your practising a song and u cant play a certain riff to speed do u practise it with a metronome or just practise it without at a speed where you make no mistakes
its best to practice with a metronome, and then to build up the speed
At first I practice only the motions of my both hands without tempo and then use the metronome to get to the desired tempo
Practice with a metronome on a slower speed, then keep increasing it when needed till you reach the original song tempo.
I just learn the riff pretty much as close to note for note as I can get, play it slowly and pick up the speed as I get more comfortable with the riff. That's how I was able to get Pantera's F'ng Hostile down as good as I do. Start slow and go through the motions and go faster till you get it. Simple strategy and it's been working for me for years!
I'd practise always with metronome, to get the rhythem right. I always have problems with that when I learn stuff :/