The more dilute the etchant is, the smoother the 'bite' and the longer it takes to do the etch. So start out with a low perecentage and if it's taking too long, make the solution stronger. If it's too strong you'll get a rough finish that looks bad.
For Ferric, I use the liquid PCB etchant and dilute it three or four parts water to one FeCl. If you are using powdered, I'd say make it about the color of 18 year old Macallan's and adjust up or down.
Degrease, in for thirty seconds, rinse, check, repeat; adjust time in the solution or solution strength. Wipe off the accumulated etching debris or they will interfere with the etch.
The copper sulfate should give you some cool effects when the copper plates out of solution!
