My method of seduction is always to show interest by joking and playing ambiguously.
In Germany, subtily showing your interest leads straight into the Berlin wall and showing your excitement is likely to make him disappear from the radar screens.
In the meantime, usually expect "no flirting and no spontaneous messages".
When a German guy is interested, he does no-thing as the game itself seems almost a strange one to play.
Playing the game of seduction with a German man: Mission impossible?