Don’t expect the photos that you snap of your children to be perfect, as many won’t be. Instead you should have an image editor on hand that you can use to touch up areas, crop, and fix any issues that may be present. For example, you could try Movavi Photo Editor.
All said and done you should be able to see the improvement to your photos almost immediately if you use the ways described above. If you want you can proceed to hone your skills further, and find other ways to capture better photos of your children as well.