Yes Marc that is often a problem on metal figures as visors tend to be cast onto the head. There is the old trick of painting a figure upside down, but that doesn't always help.
One thing I do is to paint the visor matt black which helps to clarify where I should be going with it. I hope this helps.
In fact I will say, things like that have put me off getting a figure as I knew I wouldn't be able to do the figure to my satisfaction for that reason, especially in 54mm.
A good figure and I can tell you enjoyed doing it.