The most fundamental skill in soccer is individual mastery of the ball and the creativity that comes with it.  As this skill is mastered, the rest of the game becomes easier.From a developmental standpoint, the young ages are the best ones for learning skills. Allow your players to develop these requisite skills in an environment where the main goal is to have fun with the ball. The value of matches in younger ages is that they provide youngsters with an opportunity to showcase their newly acquired skill and creativity. By the age of 15-17 the capacity to pick up new motor skills begins to wane, while the ability to conceptualize team organization, tactics and strategy increases and coaches help players to understand to use their skills to manage or gain advantage of time and space.
Consider a student in Trigonometry class who is being introduced to concepts like sine and cosine. Imagine how difficult this will be for the student to “figure out” if he/she had not been properly taught the fundamentals of math – addition, subtraction, multiplication and division. The student might even understand some trigonometric concepts, but lack the basic tools to work out a correct solution. This student should not have been promoted to this next level of math. It is the same in soccer. The success of each new skill and concept is based upon skills and concepts already learned. The more comfortable a player is with the ball, the more options he/she will have to solve each soccer challenge he/she faces.
I have been many session and seminars of Tony Decicco and David Newbery (Soccer Plus). I think they have the best approach to youth players developmental with “Skills Challenge Pyramid

“I don’t believe skill was, or ever will be, the result of coaches. It is a result of a love affair between the child and the ball” – Manfred Schellscheidt

Here are some simple age appropriated techniques players should work on.