As Montague said!

Additionally let the plane sit at idle for a while and note what happens to the engine RPM's.

If it tends to slow down over time, then the low end is too rich. A little of this can't be helped ( better that it IS a little rich ) but you don't want the engine cutting out.

Remember that the plane also leans out in flight, so keeping the plane flying is a bit of a balancing act.

It helps to perform all tuning with about 1/3 of a tank of fuel to simulate a lower fuel condition where the engine tends to run lean anyway.