Firstly, let us construct a proper model for your purpose. The skin has a very high resistance(on the order of hundreds of kilo ohms) when it is dry. However, when the skin is wet, salt on your skin is dissolved and along with water, fills the pores in your skin, creating a highly conductive path (on the order of hundreds of ohms, thanks to conductivity due to ions present in the water) through the skin. But beneath your skin, there are all sorts of conductive materials filled with ions, especially your blood.
Now, the way body works as a conductor will vary depending on how it is being shocked. If we are inspecting a microshock, for example if a catheter inserted into the heart is not grounded properly and is at a nonzero voltage, then, if the patient touches the chassis of a grounded electronic device, the path of conduction will be:
Catheter - Blood - Heart - Rest of internal structure(mostly blood) - Skin - Chassis
Now in this case, most of the resistance comes from the skin interface (Order of 10 - 100 ohms from inside the body vs. Order of 100 kohm's from the skin). However, In the case of a microshock, a few micro amperes are enough to cause the heart to enter into a state of fibrillation, killing the patient in a matter of seconds, since all of the current flows through heart.
However, if the shock is a macroshock, both sources are located outside of the body. In this case, the current will have to penetrate the skin twice, in a manner as follows:
Source 1 - Skin - Blood & Tissues - Skin - Source 2
Again, the skin causes most of the resistance, and this time there are 2 skin interfaces, causing half as large current as a microshock. However, the major difference now is that the current is distributed throughout the entire body instead of being focused on a crucial organ, therefore an order of hundred milliamps may be necessary to cause any life threatening damage.
You may treat the skin as the only source of resistance in most cases(if the skin is dry).
The life threatening aspect of electricity is more related to how the shock is applied as opposed to the magnitude of the current. There are lightning strike survivors, yet people die to microshocks every now and then.