Start with some basic ball-control movements, such as rolls, vees, toe-taps. Introduce tic-toc, if you have not already . Do your stretches, interspersed with assorted ball control moves that you want to practice.
Defensively, the main players involved are the First Defender ("Pressure player") and the backup supporting player (called the Second Defender or the "cover" player). The job of the Cover player is critical to the success of the team from a defensive standpoint. Only when Cover arrives and is in proper backup position is it possible for the Pressure player to move in to win the ball. Why? Because the backup player is available to instantly become the Pressure player if the first player is beaten. Of course, this means that the beaten player must loop around and become the new Cover player, so it is extremely important to work on this transition.
To illustrate the concepts of proper cover, put all of the players in a large circle, except for 2 players (coach can be one player for illustration). Outside players try to pass ball around, while Pressure player goes in and sets an angle to try to contain, and Cover player moves in to shut off more outlets.
Key coaching points are:
As soon as he is in position, he must shout "Cover", which is the Pressure player's key to start closing down and/or jockeying the player to the nearest touch-line. The Cover player's job is to give helpful instructions, including "Not yet" or "Don't dive in" if the attacker hasn't been pushed close enough to the touch-line to use the touch-line as an extra defender and "Now" or "Take him" when it is time to close in. It also can be useful for the Cover player to shout "Hold Him" or "Contain" as he is making the circle around, so that the Pressure player knows that help is on the way.
Note that the kids seldom talk if they are too busy concentrating on what to do, so you have made progress if you can get them to simply announce "Cover." Additionally, younger children seldom can learn more than 1-2 things at once, so you will have to judge your group. You may want to just work on the positioning, while leave training on communications for another practice if you are giving them too much to think about. Older players, or ones with more experience, may be able to handle additional training on communications.
As soon as you are getting good positioning and some communication, start working on the recovery process. To work on recovery, tell the Pressure player to dive in just before the Cover player gets into position, which will force the Cover player to become the new Pressure player. The former Pressure player then must make a proper covering run.
Play 5v2 keepaway in a narrow grid to encourage use of the touch-lines as an additional defender. Give the defenders a point for every successful steal, and give the attackers a point for 6 consecutive passes. Adjust the size of the grid to keep work-rates high. If the attackers can never be successful, the grid is too narrow while if they always seem to be successful, it is too big. Play to 3 points by either side, and then switch out defenders.
Play 2v2 in a narrow grid with small cone goals at each end, with 2 extra players waiting on the sides. Rotate one fresh player to each side in after 2 minutes; play another 2 minutes; and rotate the resting players in to replace the 2 remaining players. Let the players experiment with providing defensive support versus marking.
Coaching note: You will repeat some variation of this practice several times per year, both to refresh memories and to add additional concepts. You will find further information on fundamentals of 2v2 defensive support elsewhere in the manual .