What you may not indeed find in the tutorials at least so explicitly is that the most known cheap programmers via SPI do not have the ability to override the values of some fuses, so whenever downloading the binary code to the chip you should be careful to not turn the chip useless if it is of the SMD type (eg. it can not be removed from the board for external rewriting). One of the most common misleadings is to consfuse external clock with external oscillator.