[mistella]

yes, this is the BEST way to learn makeup.
Most people think going to school will teach them but going to school does not teach you experience and what really happens behind the scenes.
Just find makeup artists around your area & ask if they can teach you in exchange for their day rate.
If you dont want to pay their day rate & just want to assist them, thats a little harder.. You need to have experience, a portfolio and already know know the tricks of the trade. They dont want anyone slowing them down, they need someone who can ASSIST them (clean their brushes, get tissues, maybe do the model's base color) not someone who they need to TEACH on set.
best thing to do is research makeup artists in your area & give them a call!