Recording metal help?

So I have written a death metal song and am trying to record the guitar part and I cant get it to sound professional or any good. I am using a les paul/schecter, the les paul has pive pickups, the schecter has emg 81/89s with coil tap I am using a dunlop crybaby kirk hammet wah, and am sending that through an rp150 via usb cable too garageband and the rp150 is what has all the distortion and the effects. I would record it clean and then add the distortion via garageband but then it sounds weird and I cant get pinch harmonics very well. so I was wondering what would be a good preset for the rp150 to get tone similar to bloodbath (band) and also what would be some tips to make it sound more professional. I have no money.