This is a very easy game, but good practice because it uses the whole board. You need to hit every number in ascending order, starting from 1 and all the way up to 20 and bull. You can not move to next until you hit the current number. Count how many darts you need to finish all numbers.
There are some variations of this game which require you to hit 2 or 3 times in a number before you can move to the next.