With summer approaching fast I feel like eyes are the most important. They really are the only thing that can last all day to the heat, pools and lakes.
Use a waterproof, or at least a semi waterproof eyeliner and mascara.
Don’t pump your mascara (I.e.. moving the wand up and down in the tube really quickly) this will allow air to get into the tube which will cause your mascara to dry out.
The #1 reason for flaky mascara is that the formula is too dry or old. Make sure to close mascara after use to help keep its moisture. To extend the life a bit, add 2-3 drops of saline solution into the tube and swirl the brush around.
Don’t use a cream eye shadow, they get melted in the summer. If you apply an eye primer with a powder shadow, it will lower the chances of seeing that crease and last all day.