1) Be very descriptive, this repository is home to lots of awesome algorithms ranging from beginner to advanced difficulties. Explain the algorithm that you solved with comments, explanation, diagrams or whatever to help the newbie programmers understand it without any hassle, like you were explaining a 5 year old kid (ELI5). Remember, we're a community that help each other, you're a teacher to the ones that need help and vice versa.
2) If you come across a problem somewhere, make sure you mention that.For ex, if you came across a problem from a book, mention that book.