In what ways can you make your penis bigger naturally ?

None other than: Puberty and erections.

No reliable means: Even surgery turns out to be of limited value for most. There are stretching devices which can provide modest increases in length like on the order of a 1/2 inch but they require rigorous use regimens and they can lead to very serious complications. Try not to focus on size as it really only serves to handicap you from a psychologic perspective.