Here we will collect some tips and tricks for useful tank layouts.
The big question after buying a new tank is "What equipment should I buy?".

I will try to give some helpful hints here.

General hint:
Most lower tier tanks are just "walkthroughs" and steps on the way up, so I do not recommend to buy any equipment, that can not be moved on the the next higher tier tanks.
A good equipment for lower tiers is the camo-net. It is not too expensive and I would say it is mandatory for SPGs and TDs.
But you dont have to buy more than two of them (at the beginning). Just two clicks around and you moved it from one tank to another.

(Re-)Moveable equipment:

Camouflage Net
Binocular Telescope
Toolbox

The telescope and toolbox dont make much sense on most of the lower tier (I to IV).
There are always exceptions, like scout tanks (T-50, Leopard), that may have a benefit of the binoculars, if you play them in defensive, hidden mode.
But (just) for scouts, the "coated optics" may be worth thinking about, because you have more benefit of it and you will have to spend much time in these tanks, while grinding up to T-50-2 or VK2801.

German Tree

TD
- Panzerjäger I --> Camo

- Marder II --> Camo

- Hetzer --> Camo + 10,5 with HE

- StuG III --> Camo + Binocular + 7,5 cm StuK 42 L/70

- JagdPz IV --> Camo + Binocular + 7,5 cm StuK 42 L/70 or 8,8 cm PaK 36 L/56

- Jagdpanther --> "break even" for camo, better invest in Vent / Rammer / GunLayingDrive + 8,8 cm PaK 43 L/71

- Ferdinand

- Jagdtiger

SPG

General thoughts: Like for the TDs, Camo is a "must have".

- Bison --> Camo

- Sturmpanzer II --> Camo

- Wespe --> Camo

- Grille --> Camo

- Hummel --> Camo, Enhanced Gun Laying Drive, Tank Gun Rammer

- GW Panther

- GW Tiger

- GW Typ E

Mediums

Heavy

USA Tree

USSR Tree

French Tree