Disclaimers

Components

You may probably purchase lot of electronics on Aliexpress. If so (and even if not), I encourage you to test every device you buy (GPS, Sensors, MOSFET, etc.) on a breadboard to ensure they are working properly BEFORE soldering them on the board. Space for soldering is not that big, and having to unsolder a 4/5 pins component is quite a hard job... For example, the GPS I first purchased was not working so well (very slow, etc.) and the accelerometer was not working at all, and with a wrong I2C address.
Female pin headers can also be used for some components (GPS, Accelerometer, etc.), even if I did not use.
Before soldering connectors (GX12-Y, DC, Buttons, etc.), BE SURE they are already in place on the case! That can sounds stupid, but once soldered you won't be able to mount them.
Once connectors are mounted and soldered, ensure that no wire is touching another one (with multimeter) and use hot glue to ensure that wires won't move during assembly.
By default, no Jumper component should be used. Each Jumper component allows to bypass a functionality. Please refer to Electronic Schematics of AstroPi Cube to understand the functionality before deciding to bypass it or not.

There is not a lot of free space in the Astropi Cube. I encourage you to use the smaller wires possible for the current needed:

20 AWG for ALL 12v power inputs / outputs connectors. This includes all DC connectors, GX12-2 connectors, switch buttons and Dew Controllers
22/24 AWG for Dew Controller's GX12-3 probes
22/24 AWG for modules' GX12-7 connectors. Please read carefully GX12-7 connectors disclaimers

Soldering the AstroPi Cube's PCB to the GX12-7 connectors is the trickiest part: I used 20AWG wires and that was... quite hard.
Even if AstroPi Cube provides GX12-7 outputs, no modules will actually use the 7 pins in same time. Be smart and build GX12-7 to GX12-Y cables: 'Y' being the maximum needed module wires. For example on capture bellow, only 4 pins are used on module side (1, 2, 6, 7).
No need to use GX12-7 on the module' side if only GX12-4 is needed, because GX12-7 are harder to deal with. BUT be careful that correct wire mapping is done between numbers on AstroPi Cube's PCB and on the module's PCB.
In the example bellow, you should test with multimeter that, once GX12-7 to GX12-4 cable is plugged to both AstroPi Cube and Module, that:
- Number '1' connects to number '1' and NO other number
- Number '2' connects to number '2' and NO other number
- Number '6' connects to number '6' and NO other number
- Number '7' connects to number '7' and NO other number
- Of course, test it when AstroPi Cube is turned off.