The [hopefully definitive

] comparison of the various ways (outside of club practice) kids have of getting extra touches on the ball. Feel free to provide input. YMMV. I'd think ideally a kid should have a mix of these during their soccer education.
Self-Practice (e.g., banging against a wall, Coerver exercises). Pros: cheap; repetition is a great way to improve; some kids are mature and/or motivated enough to do it. Cons: Could be boring and hard to keep the kid's attention; can't practice certain things without a partner; might learn bad habits if no correction.
Practice with Parent. Pros: cheap; parent might have best idea what coach wants kid to work on; good way to bond and spend time with the kids; parent might be easier to schedule than more organized activities. Cons: Parents might not really know what kid needs to work on or might not fully understand the technique, particularly if they haven't played; some kids push back on parenting.
Camps. Pros: can be fun; meet other players; might learn new things; can work on techniques which require more than 1 person; taught by people with soccer experience. Cons: without repetition and reinforcement techniques learned in camp can be easily forgotten; might not be worth the bang for the buck; even if the head coach is great assistants may not be; talent levels may vary greatly; some camps are more serious than others; claims of ID sometimes are dubious.
Recurring soccer clinics and small group training. Pros: cheaper than privates; recurring reinforcement of techniques learned; can work on techniques which require more than 1 person; taught by people with soccer experience and with motivation to keep customers coming back. Cons: you have to work on things which the instructor wants to work on and not necessarily things you need to improve on; talent level and needs within the group may vary.
Privates. Pros: can work on techniques most immediately pressing for the player; taught generally by people with soccer experience (but you get what you pay for) and with motivation to keep customers coming back; way to get individual attention. Cons: can't recreate scenarios involving more than 2 or 3 people; insurance quality may vary; can be expensive; teaching quality may vary; may not necessarily know what the player needs to work on.
Pickup Games: Pros: great way to have unstructured, creative exploration and self-learning. Cons: hard to arrange in this day and age; liability concerns; usually no correction or supervision of technique.