If applying a sunscreen to your face or a child over six months, then it is best to go with a non-comedogenic (does not give comedones or acne) sunblock that contains only the following two possible mineral block ingredients: zinc oxide, titanium dioxide. If your sunscreen/block has more than those ingredients it may be irritating or even toxic chemicals. Toxic to both humans and the environment.
If applying sunscreen or block to your body, you can use the same mineral blocks explained above.
Most importantly, do not rely on sunscreen/block alone for sun protection. It is best to also use hats and clothing and shade for protection.