4. Make sure you have proper lighting
When you take a photo in low light or with a higher ISO your picture will be grainy.
And grainy pictures are not and never will be sharp no matter how much you click the sharpen button on your editing tool.
I had to learn this the hard way.
I took all these pictures for a magazine once with my ISO set to 3200 by accident. When I went to edit the photos, no matter what I did, no matter how much I lightened them, they were never going to be sharp.