The front and side exercise kicks are not intended to be fighting techniques; they are awkward and weak. However, front and side exercise kicks are excellent dynamic hip stretches, and they are excellent teaching tools for other kicks. You need to be able to something before you can do something well.
Front exercise kick
To execute a front exercise kick, enter a front stance with a cross-body block. Then, swing your leg forward from the hip -- and only from the hip -- the knee and ankle remain locked. Try to kick as high as possible. Keep your back perpendicular to the floor, and try to knee yourself in the chest. Keep your toes curled back to expose the ball of the foot. When the kick has completed, reverse the process by swinging the leg down and back into a good front stance. The video below will demonstrate:
[video of a front exercise kick slow and fast from the front , and from the kicking side]
Side exercise kick
[photo of attention stance with a side guard. From front and side]
Then, rotate your leg up to the side, again locking the knee and ankle. Arch your back as you swing. For maximum extension, rotate your supporting foot so that your toes point towards your head. It seems silly, but the results are drastic:
[video of a side exercise kick slow and fast from the front, and from the kicking side. Follow with a closeup of the pivoting foot. Demonstrate a side exercise kick slow, from a front view, with and without a foot pivot]
When kicking, point your big toe up and your other toes down, to form the sokutō. As you kick, switch your hands -- press down with the leading-side hand to protect your groin, and raise your other hand to protect your face. Reverse the process as you return to attention stance to complete the kick. These hand positions will not protect you, per se, but the act of transitioning between the two will swat an opponent’s attacks away.
Avoid leaning to the side to increase the kick's height. Side exercise kicks may be harder to do without leaning, but the entire point of doing them is to improve your sense of balance and stretch your hips.