These skills are an array of skills which tackle the process of organizing and taking in new information, retaining information, or dealing with assessments. They include mnemonics, which aid the retention of lists of information. Effective reading; concentration techniques. More broadly, any skill which boosts a person's ability to study, retain and recall information which assists in and passing exams can be termed a skill of studies. And this could include time management and motivational techniques.
These skills are discrete techniques that can be learned. Usually in a short time, and applied to all or most fields of it. They must therefore be distinguished from strategies that are specific to a particular field of it.