Well, I said that advice is always free !  Of course the pat answer is to say look at the packing instructions on my website, but for those who don't want to bother - I always ask the sender to immobilise the carriage with the carriage lock if there is one, and maybe use elastic bands to tie it down too.  A favourite trick of mine is to cut a cardboard quadrant to go into the type basket to hold the typebars down.  Masking tape across the spools stops them unwinding.  And a MINIMUM of two inches of bubblewrap or crushed newpaper balls top/bottom/front/back/both sides helps to prevent damage.  The acid test is to make sure you can't hear or feel the machine moving in its' box whern you shake it.  If you can shake it - the Post Office will break it !