This is downright pathetic.
Students need to be supervised. Low time pilots are not, should not be, and can not be supervised.
Simple point 1: The commander is PIC. As a PPL, you are always unsupervised; nobody else is responsible for any of your actions. Ever. In that regard, the task of a PPL is more difficult than that of a fresh airliner pilot; you are PIC from day one. It is imperative that this is understood.
Simple point 2: You don't fly VFR in IMC (Special VFR excluded...).
Simple point 3: You follow the regulations concerning fuel planning on cross country flights.
Simple point 4: You follow the regulations regarding weight and balance.
It is by keeping the above points simple that you avoid accidents. When one starts arguing that "it is not that simple", one is not explaining the previous accident; one is contributing to the next one.