Basic Communication Skills.
While there are other technical skills that will surely help anyone succeed in life, nothing beats "communication skills". On this day and age of technological advancements, people now lack the skills to properly express their thoughts and opinions in a way that will not be misinterpreted by other people.
Communication skills are also helpful in surviving in a place that you are not familiar with. A great example would be a first time foreigner visiting a foreign country, without basic communication skills, how will he be able to communicate with people from there? How will he survive?