The wooden Plane works by taking off very thin layers of material shavings when pushed along the material, and with Japanese planes, it removes the shavings when pulled along the material. This process allows you to remove the material to straighten and smooth it to give a nice clean finish.
You will notice that when you are planning the material, the excess material comes up from the neck of the Plane, so it is important to keep your Plane sharp and remove the buildup of shavings when planning. The throat lever is in front of the cap; if your Plane is set to cut a lot of material, the material will be harder to remove; always set your Plane to remove the thin strips, and the result will be a clean and smooth finish.
Keeping the edge of cutting iron as close to the sole as possible will really help avoid unnecessary splits; Be careful not to "choke" the Plane. Choking your Plane occurs when the shavings being removed become stuck in the mouth of the Plane and will result in splitting and damage to the surface of the material being employed.