Engraving Slate with Sculpfun

Guys, please help.
Just recently joined and have Sculpfun S30 pro 10w.
Was trying to engrave slate. Found it very hard at the beginning. Settings all over the place as there are so many different opinions.
Saw big improvements lately with trial and error. More error!
My latest settings were 1500/35 on fill.
I would still like to get it a bit sharper on the edges.
Any ideas, opinions I can start with.
Just using old roof slate to practice at present so perhaps not the best material!!
Thanks in advance