While Andrew is mentioned along with the Twelve, usually in conjunction with his brother, Simon Peter, he appears with particularity three times within the Gospel of John. When the curious Greeks wish to speak with Jesus, they first approach Philip, who then approaches Andrew, and the two of them then mediate with Jesus (John 12:20-22) about the meeting. Before Jesus feeds the five thousand, it is Andrew who brings forward the "lad with five barley loaves and two fish." (John 6:8f). Also, Andrew is the brother to first meet Jesus and the one to take that news, and the holy invitation, to Simon Peter (John 1:35-42). It is Andrew who first proclaims, "We have found the Messiah".
Thematically, on each occasion when he is mentioned as an individual, it is because he is instrumental in bringing others to meet the Savior. This has long been regarded as the specific ministry of Andrew, something recognized in the Episcopal Church through the Fellowship of Saint Andrew, an organization devoted to encouraging personal evangelism and inviting one's friends and colleagues to a knowledge of the Gospel.
Several centuries after the death of Andrew, some of his relics were brought to Scotland by a missionary named Rule, to what is now known as St. Andrew's, popularly recognized as the site of world-famous golf course and university. Hence, Andrew becomes strongly associated with that northern jewel of the British Isles. [Having a Scottish mother, I had to say that.]
According to pious legend, Andrew was crucified on an X-shaped cross, as represented on the design of the official flag of Scotland.
Sorry, Wales and St. David. You got left out.