A good resolution for 2018 would be to understand resolution.
I encourage people to deal with images by their pixel dimensions rather than arbitrary definitions. For example, you may be asked for a high res file, but not given a size. You need a size and intended use for the image to make a decision.
1200×1800 pixels = 4×6 inches @ 300 ppi
1200×1800 pixels = 16.667×25 inches at 72 ppi
Bryson Leidich 