I put it on with my BB cream and blended them together so I can put it all over.
Honestly, I think for this product specifically you can do either. I've always used it all over, however because it brightens you can apply it to your cheekbones.
Put some on your finger and coat it lightly on your face; or, mix a little with your liquid foundation; or dab some on as a highlighter. It all depends on what you want to use it for, how subtle you want it, and likely your age. I think it's a nice product - I vary it depending on what makeup I am doing - going to work vs going out, like that. It is not overwhelming or sparkly and such by any means so I would say give it a try!
Well, primers are generally an all-over product to prep the skin for foundation. There are many kinds used for different effects- However, the use of this one may really depend on your skin type and your intended effect. If you have oily skin, I actually may not recommend this one at all; if you want the dewy look on cheekbones, perhaps apply only on that area, then a different primer on nose, chin, forehead, etc. It's not super shimmery but may produce a dewy effect more readily than other primers, so if you want to extend the life of a shine free face, try a different product.