Cleaning water based cakes?

Hi guys! Now please bear with me here while I tell 9you a little bit about myself.
I'm a 16 year old wanna-be makeup artist. I love beauty makeup, special effects makeup, as well as recently getting into face painting. I have my first face painting 'job' tomorrow at around 5 for my cousins first birthday party. I have a few questions in which google has failed to give me the answers to   
So my first question is- If i am using water activated/water based paints, how to I sanitize the paints between each kid? I know some would prefer to not sanitize between clients, but I would like to. Can I use alcohol to sanitize water face paints? I have a spray bottle of water and a separate brush for each color spectrum? (pink and red have one, etc).. But double dipping would be an issue so I'd like to sanitize the cakes before moving on to the next person. How should I go about doing this? Alcohol, as I've read is good for this, but if it's water activated, will it affect the application or texture?
Whew. Well those are all the questions I have for now. Thanks for reading and any answers you may have!

Alyssa, there is no need to sanitize the cakes, they are made to have anti-microbial agents so not to grow bacteria. Just plain water is sufficient and allow the cake to dry completely. Using clean brushes for each client is best and avoid double dipping. If you notice a client that has open sores or is sick, do not paint them, and if you accidentally do, retire that brush until you get a good cleaning on it with soap and hot water and a dip in rubbing alcohol and then air dry.

Your paints (if professional grade) should have an anti-microbial agents in them. This will help, but ideally you want to wash or sanitise your brushes. Different artists do this different ways.

In the makeup world as you know there is NO double dipping with 'wet product' everything is put on a pallet with a metal spatula and used from there. But this type of proceedure isn't feesable with face painting. So we want to focus on cleaning the brushes most of all.

Some people carry LOADS of brushes to an event and clean them after.

Some use a 3 cup system - one cup rinse water, one cup alcolhol and 1 cup for freash water.

Some use brush bath or soap in between.

Some use a spray bottle of 99% iso to soak the brushes with

Some mix their iso and water (but this does nothing and can be hazardous to the skin).

Depends who you ask.

You can also use a spray bottle of 99% iso to sanitise your paints with a spritz, but if you over do it, your paints will dry out big time.

Also make sure you are painting on a clean face, and never paint over sores or wounds of any kind, EVEN if they have scabbed over. and NEVER paint a person who is sick. Carry stickers in your kit for these occurences and have this posted on a sign at your table. If you start painting and the kid starts to caugh or sniffle, finsih quickly as you can, and sanitise EVERYTHING that may have had contact with them before you continue, including the chair they were sitting in.

If you paint near the eyes or mouth you must fully sanitize your brushes. 

Use one sponge per person, and hand santizer between kids. Finally you have to actually wash your hands from time to time. I have a spray bottle of soapy water for this, and a towel with my setup.

good luck!