Applying sunscreen before going outside is only part of sun protection. A little planning makes it easier to combine sunscreen with shade and clothing when your day changes.
Check your plans
For time outdoors, follow the product label and reapply regularly; the American Academy of Dermatology recommends reapplication approximately every two hours and after swimming or sweating. Carry the product with you when you will be away from home.
Make the routine workable
Choose a broad-spectrum, water-resistant sunscreen with SPF 30 or higher. A hat and shade are useful companions, not reasons to skip protection. Makeup with SPF can add coverage, but it should not be your only plan for adequate application.
Remember exposed areas
Ears, the back of the neck and the tops of the feet can be easy to miss. Check the label for application directions, seek shade when appropriate, and use clothing and a wide-brimmed hat where practical.
Further reading: American Academy of Dermatology.