Mark is short + punchy. It goes from story to story and is full of action. He writes to "Gentiles" (people who didn't have much religious knowledge), and leaves the book ending on a cliffhanger. This is a good place to start!

Matthew was a religious history buff and wrote about Jesus' life using heaps of references to the Old Testament (the religious laws and stories that said someone was coming to save God's people). He wrote to the Jews of the time, to prove that Jesus was fulfilling all the prophecies of being the one to save God's people, but in a different way than what they expected.

Luke was a doctor and so was very detailed in his telling of the story of Jesus. His writing fleshes out many of the stories and his specific details are to prove the historical accuracy of the text and to prove the legitimacy of the stories. Many of the same stories of Jesus are told in multiple books - if you're lost with a story in Mark/Matthew/John, try looking for it in Luke for the expanded version.

John was a real interesting guy as you’ll find out from his intro. He writes to prove that Jesus was both God and human, using language and stories that God had used to describe himself in the Old Testament, and using them to describe Jesus. John is the most different out of the four, so you'll find different stories in this book than the others.