Their are a lot of threads on how to play Germany, just go back a couple days and you will find a lot of topics that will help.
Easy fast tips:
#1 I start building infantry divs from the start. start the game by building 40 divs. Then put your IC to 70% tech and 30% building your inf divs. Keep what ever IC you need for supplies and consumer goods as well.
#2 Research only techs you need. Pick one style of fighter and stick with it. I go with intespters. Don't wast IC on crappy techs that you don't need, like heavy bombers or navy techs.
#3 Don't build any armor until you finish researching the basic type of tank you want. Some people like light tanks some med some heavy, I research med tanks and once my basic is researched then I start to build them. They usually start rolling off the line in time for France but not in time for Poland. I normally attack Poland with Inf only.
#4 If you keep building your Inf and wait to build your planes and tanks until your first prototypes are done you should have around 100 to 120 inf divs to attack Poland and beat them easy. Then your good stuff will start rolling off the line in Oct or Nov 39 in time to mop the floor with France and then attack who you like
#5 as each year roles by add more IC to building and less to techs, by 1939 you should be around 50-50 or 60-40 in favor of production.