• Roberto I am not a mechanic but as far as i know there are only a very few things you should never ever grease:

    1) BB spindle tapers
    2) when pressing headset cups
    3) saddle rails / stem clamp

    And I do the exact opposite. (except the stem clamp)

    1) BB spindle tapers - to create a seal between aluminum and steel and to insure they go on all the way, just know how much to tighten as to not overtighten.
    2) when pressing headset cups - again sometimes it due to aluminum and steel contact and to form a barrier against rust or corrosion.
    3) saddle rails - many annoying creaks have been solved this way.

About