You are starting a game of diplomacy, and you have Germany. I hope you have played before, as I find Germany one of the more difficult countries to play, it is also a very fun country to play. This is also reflected in the number of neighbors you have: five of them. Only Turkey is of little interest for Germany early in the game, all the other countries are close by.
Germany is part of the northern triangle, with England and France. But Germany also has significant dealings with Austria and Russia. Italy, via Tyrolia, could become a threat to Germany quite early in the game as well.
Germany – Austria relation
Austria is a true friend of Germany early in the game. As both countries are central powers, they both have plenty of challenges on their own. I have seen extremely little games where either Austria attacked Germany, or vice versa. This is mainly true in the first 4-5years of the game. Usually you will be on speaking terms with Austria and try to exchange as much information as you can, especially about your common neighbor Russia.
Germany – Italy relation
Italy is also a central power, but different than Austria. There will be quite a few players that move the Italian army to Tyrolia in spring 1901. Although this is usually with the intention to attack Austria, it is not something you should like as a German player. You now suddenly have an Italian army that could invade Munich.
As Germany, I would try to convince Austria and Italy to work together. Although this might be hard to achieve, it will give you peace and serenity on your southern border, which means you can focus on other activities.
Germany – France relation
Your main meeting grounds with France are in Burgundy and Belgium in 1901. An aggressive German player moves to Burgundy in spring 1901, giving you opportunities towards Belgium/Paris/Marseille in the fall. Normally, this means war with the French. However, a French army in Burgundy in Spring 1901 you want to avoid, as it forces you to cover Munich, giving you a weak position towards Belgium and maybe even Holland.
I believe the best strategy for Germany is to either befriend England or France, and go and attack with the two of you number three. However, please be aware that you could also be this number three if England and France join forces.
Germany – England relation
England and Germany can either be allies or enemies, something in between is difficult if you ask me. I personally prefer France as an ally, but I have seen plenty of great alliances between German and English players. Normally it would involve a division where England focuses (with German help) on Scandinavia, and England helps Germany to seize Belgium. A key weakness for Germany is that this alliance can only exist with the German player not building any fleets. However, it is difficult to turn that around in the later stages of the game.
Germany – Russia relation
Russia is a difficult neighbor. I would normally try and establish both Prussia and Silesia as DMZ’s early in the game, but if you do not trust the Russian Czar, you could also decide to move Berlin to Silesia in Spring 1901. In case you decide this, it is crucial you move your fleet in Kiel to Denmark, so you can bounce the Russians out of Sweden, denying them a build in 1901.
An important relationship is between France and Russia. You do not want there to be an alliance between France and Russia, as it is usually directly aimed against you. Although you might be able to ask England to help you against this alliance, they will be less threatened by this. Make sure you stay informed about how the Russian-France contact is going and do your best to prevent this.
Russia could be extremely helpful if you see and English-France alliance developing, as he could put significant pressure on England in Scandinavia.
I personally believe in a long term alliance between Russia and Germany, as together they can go after Scandinavia/England and later also Austria. However, be careful for a Russian player that grows too fast, as his corner position gives him a strong tactical advantage against Germany.