Here are mistakes I see beginners make repeatedly: Forgetting to convert input. int(input()) not just input() when you need numbers.
Off-by-one errors with range. range(n) gives to n-, not to n.
Extra print statements. Debug prints left in your code add unwanted output.
Wrong variable names. Typos like pritn instead of print cause errors.
Missing quotes around strings. print(Hello) fails; print("Hello") works. Check these first when your code doesn't work.