there are five people in my family,beside myself..

除了“我自己”,就是说除了本人,所以这个意思就用Self了.
有些地方看上下文意思需要强调说“某人自己”的一般需要Self形式
用法
1）做宾语
a.有些动词需有反身代词
absent,bath,amuse,blame,dry,cut,enjoy,hurt,introduce,behave
We enjoyed ourselves very much last night.我们昨晚玩得很开心.
Please help yourself to some fish.请你随便吃点鱼.
b.用于及物动词+宾语+介词
take pride in,be annoyed with,help oneself to sth.
I could not dress (myself) up at that time.那个时候我不能打扮我自己.
注：有些动词后不跟反身代词,get up,sit-down,stand up,wake up等.
Please sit down.请坐.
2） 作表语； 同位语
be oneself:I am not myself today.我今天不舒服.
The thing itself is not important.事情本身并不重要.
3） 在不强调的情况下,but,except,for 等介词后宾语用反身代词或人称代词宾格均可.如：
No one but myself (me) is hurt.