How can I get better vision natrally?

Some options.... Some options to "naturally" improve one's vision include making sure one has all of the daily requirements of vitamins and minerals (taking a multivitamin will help with this), taking ocu-vit vitamins, and taking fish oil supplements (some studies have shown that fish oil supplements may help with eye health.). Lastly, wear quality sun glasses whenever outdoors to protect the eye from uv light.
You cannot. There are no ways to "naturally" improve your vision. There are things you can do to prevent damage, like keeping a healthy diet, exercising and protecting yourself from uv exposure. The only way to improve your visual acuity without glasses or contacts is surgical vision correction.