Help w/winding hand wind Luminor Marina

[David]

Hi,
I just received a 1998 era Luminor Marina Hand Wind watch.....I noticed it has been losing about 20 at night.  I wonder if I'm winding it correctly......Is it as simple as winding the thumbscrew clockwise until it gets difficult to turn, or it there some other technique that I am unaware of?....I don't think the watch has been used for some time so I don't know if that should have anything to do with the time loss........Please Help..Thanks in advance....David