On the bright side, this trait makes them very reliable, as what has been decided or agreed even just verbally with them is more or less set in stone and will be respected. They will expect the same rigour and organization from you.
At the core of the German business culture is the notion of compromise. Managers do not take decisions unilaterally but prefer collective decision-making which makes their subordinates feel involved and appreciated. This might lead to some delay in their decision-making process; you must be patient. Moreover, while negotiating, Germans – unlike for example the French or the Italians – will avoid conflict and confrontation and will most of the time seek compromise and mutual benefit. They won’t appreciate a confrontational and emotional approach in negotiation so go for a factual, rational and detached argumentation to convince them.
Communicate, communicate, communicate.The Germans are very detail-oriented and generally appreciate careful planning as said before. It is very important that you regularly keep them informed, either by email or by phone, of your decisions and advancements so as not to give them the means to plan their moves accordingly. They are not particularly good at improvisation which makes communication even more important to them.
Punctuality.The German vision of time is very rigid. If you are on time, you are already late: the best thing is to always be five to ten minutes early. This might sound obvious but perception of time actually varies greatly from a culture to another. Finally, with all that has been said, it will not come as a surprise to you that deadlines are binding and to be met at all costs.