Soap irritates the tissues of the inside of the foreskin and the glans -- think about washing the inside of your eyelid (same tissue) with soap. Irritation from soap leads to more production of smegma, leads to more odor, which can lead to you washing more with soap.
Use warm water. Pull your foreskin back and rinse it carefully, making sure you have removed any build up of moisture, or smegma. If you stop the use of soap and rinse regularly for a week or so, you will not feel that you need soap again, and your foreskin will be healthier. I haven't washed my glans and foreskin with soap for more than a decade, no smegma build up, no bad odor. I pull back my foreskin and rinse my cock before sex, just to be sure I taste good.