As a rule of thumb products should be applied from lightest or thinnest to heaviest or thickest. Always start with a clean slate aka face. If your cleanser is not pH neutral, use a toner to set it back to a neutral pH. Next consider a serum - usually packed with goodness for your skin such as vitamins, antioxidants, hydration. A lotion or cream should add moisture and protection to your skin and seal in hydration. Alternatively, a face oil may do that job (depending on your skin type and needs). Lastly: sun protection. Allow for each product to soak in before you add the next layer. Makeup should be applied last. Happy layering!
It is the single best thing you can do for your skin. Look for broad spectrum UV protection to protect from UVB 'burning rays' and UVA 'aging rays'. Chemical filters penetrate your skin where they absorb sun rays, so allow for approximately 20 minutes before sun exposure. Physical sun screen sits on the skin and reflects the rays. Zinc oxide and titanium dioxide are the ingredients to look for. No worries, these days physical sunscreens go on fabulously sheer. Remember, UVA rays penetrate glass, so whether you are inside or outside, rain or shine, SPF is the way to go.