Here are some tips for how to prepare for a shoot, even a week before it.
If you are modeling legs, feet, hands, etc. it is best to prepare before. Sometimes even getting an extra pedicure that isn't even meant for the shoot is a good idea, it will clean and prepare your feet and refresh them, then get another one the day before the shoot. The extra money is worth it. Same goes for hands. Moisturize with creams and try not to wear as much makeup before the shoot because you want to keep your skin blemish free and clean for the day of the shoot. Makeup is a big reason models get pimples, so make sure you have your own foundation even prepared and brushes, and even a little mini makeup kit because you don't want to share brushes if possible. Or at least clean your face right after the shoot.
For scars, try the cream Scar Zone, and remember sprays like Sally Hansen's Airbrush Makeup or Airbrush legs can be a good instant fix too.
Eyebrows- I hate tweezing and I hate waxing them, so if I need a quick fix I use a brown eye shadow to fill in the areas that need it, or to shape them.