"帮他准备早餐"的英文表达方法有几种：

prepare breakfast for him
make breakfast for him
fix breakfast for him

其中，"prepare"、"make"、"fix"都可以表示"准备"的意思。

举几个例句：

I'll prepare breakfast for him while he gets dressed. (我会在他穿衣服的时候为他准备早餐。)
Can you make breakfast for him this morning? (你今天早上能为他准备早餐吗？)
I'll fix breakfast for him before I go to work. (我会在去上班之前为他准备早餐。)