Hello Frank and welcome to the Forum :)
Please don’t wax the helmet. In my eyes the patina is part of it’s history and shouldn‘t be polished away. However, in some cases the condition of a helmet is too bad and restoration is the only option. In order to estimate this we need to see pictures of the helmet.
If you decide to restore the helmet, please try using materials from the past as new ones often contain chemicals that could damage the original base. Further you should keep in mind that a missing patina or a restoration can reduce the value of the helmet, as most collectors these days prefer the original condition with patina.