[laiocfar]

First german tanks(Pz I and II) arent up to fight even polish. Pz III are an acceptable anti-tank unit but only Pz IV(Norway) are a decent multi-role tank.

Use your infantry but be sure to be able to retreat when attacking entreched units(move in and dont fire first turn or have artillery support). With that you can complete both polish battles. Anyway build some tanks to kill already damaged units for the experience. Polish are easy, just remember to lock on your objetives. In first scenario upgrade your tanks(2-4 units, no more, no less) and build infantry.
My attacking logic is to use tanks to clean antiair, artillery and a single square next to city to prevent reiforcement, infantry will attack town from there. If tanks fails to clear antiair, artillery and eventually infantry will aid. If tanks fail to clear artillery, air force will air. If the city is defended by and experienced and entreched unit, only attack if most of them get supressed or killed by air or artillery.

Veteran infantry and artillery will be the key into capturing towns or fortifications. Your army need to have always near 6 inf divisions and 3 of artillery, they are the specialist in rough terrains and house-to-house fighting. During the second scenario, complete your army and add some fighters, tactical bombers are more usefull but experienced fighters are needed in futher battles. I always love to build early para, they can result a pain for the best AI if you are clever when using them.

Norway is a really hard scenario, my suggestion is to not attemp a decisive victory if you are having problems in poland or dont even attemp a victory if you got problems with the game; better concentrate in building up your tanks divisions. You may divide your attack force in 3 and you got 5 big problems to solve... may best result in this battle was a decisive victory but with many losses.
Deploy point A and first problem: Oslo, your troops may land and assault the city from a river under artillery and air bombardement. Experienced pioners or enginers are the solution but more normally you will be forced to use normal infantry with artillery support and take several losses that will slow down you.
Deploy point B: Bergen, defenders are few and air support is given by norwain planes so a piece of cake.
Deploy point C and problems 2 and 3: Trondheim, you may land far away from the city, near none opposition while landing but strong air support and from british planes plus your planes arent able to get there. The city is defended by Nor troops but since the royal marine is there, it will be near impossible to attack. The british air bombarment cant be avoided but you can try something on their navy. Your own naval units are divided but you got submarines. So you can unite your navy and defeat the royal marine later in the scenario leaving you few time for attack Narvik and Trondheim, or launch them one by one without chance of winning but giving your land forces the chance to attack and capture Trondheim early in the game.
Problem 4: when your troops from Bergen and Olso join to attack Lillehamme(the inland objetive between Trondheim and Oslo), bad weather will leave you unable to cross rivers without a bridge and to use air force. The only bridge is well defended, you distract tanks from Trondheim and Narvik slowing you advance or have your forces divided longer resulting in less troops advancing towards Narvik and slowing your advance.
Problem 5: Narvik is defended by british troops, air units and fleet, plus there is a narrow pass that slowdown your troops.
You can chose to dont deploy in point C and lost the battle without risking your troops. Paratroopers can aid you in Lillehamme with the only risk of enemy interceptors or in Narvik where they are more likely to get killed.

Low countries, is the easiest battle. Here you can fully fit an air division with tactical bombers, train a new tank division, build some more land troops and/or train a big paratroopers division(no more than 3-4 coz you arent given more transport planes). Just remember to assault well entreched british or french units in towns with veteran infantry and use your veteran tanks with full of support to kill french and british superior armor ones.

France campaing will be the result of your previous actions. You will face strong resistance in the border and in each city, you will defeat it but the time is crucial. You may divide your forces again and move quickly. An strong paratrooper division can capture a deep objetive and decide the battle.

Always look after your units, they worth nothing without experience so dont take risk, later in the game you will be able to wipe out entreched AT with your ultraveteran King Tigers Pz VI.

Wow, it looks like i wrote a bible, sorry guys