A few important things about inletting, and I'm sorry if it was covered somewhere else, is first you need to learn to interpret what your inletetting black is telling you. Since the goal is to make the metal look like it is growing out of the wood, without any unsightly gaps, the black will transfer to where the part is fitting perfectly as well as where wood (or metal!) needs to be removed. So you need to interpret which black to remove and which black to leave alone. A simple rule I follow is to remove all of the black at the bottom of the inlet and leave the black alone on the sides until you are no longer printing on the bottom, then determine if the sides need to be addressed. This will give you a greater margin of error since it is generally easier to fix an inlet that is too deep rather than one that is too wide. When looking at the black on the sides of an inlet, there are going to be spots that are considerably darker than others, those spots are where the metal part has pressed into the wood over and over again and are areas I would address first, prior to areas on the sides where the black is not as dark.
Next, don't underestimate simply feeling the part, it's surprising how much information you can gain through your hands just by pressing the part into the wood and feeling what it's telling you.
And finally, there are any number of ways of fixing mistakes that you won't even see when it's done. The important thing is to put the gun down, sleep on it, and come looking for an answer in the morning.
