Stock nozzle is 0.4mm. 0.3mm should be a good start for layer height.
Several things can cause layer separation:
Hotend temp too low
Try 200c hotend and 60c bed if using PLA. That is a good general starting point.
Z steps not set correctly (too low)
The Z steps should be very close to correct in the stock firmware and should not cause this issue.
Also, stock extruder steps should be good as well if using the stock hotend and extruder parts. Set your extrusion multiplier to 1.00 or 100 depending on your slicer.
Note: I moved this into the correct section.