Last night I received an email from our guitarist with an mp3 looping an absolutely disgusting, sludgy, doomy guitar riff. It sounds great but because he's gone so low with it, he's pretty much playing a bass part on baritone guitar (tuned to A#). This means the space left for me is pretty much a lead part which is something I have zero experience writing. Are there any good guides or rules or tips for writing a lead part? Or is it just a case of put it on loop, pour a whisky and jam until something happens?