First and foremost - makeup should be applied to all regions of exposed skin that are not covered by clothing - so don't forget your neck. Also, make sure that it is thoroughly blended in - a high resolution 10x8 headshot photo will pick up any faults in your makeup application
Its a good idea to apply makeup primer such as Revlon Photoready Perfecting Primer. Applying concealer before the foundation will give a smoother look. Rimmel Match Perfection 2-in-1 Concealer is handy as you won't need a lighter colour for your eyes.
Tips on Concealer and Foundation Application
Matt formulated foundations, such as Bare Minerals, are a must. There are also special formulations of foundation for photographic use such as HD Forever. For a studio photo shoot, it will be neccessary to apply your makeup slightly heavier than normal. The aim is to get a natural looking effect - normally applied makeup will look washed out under studio lighting.