I had a rule of thumb as a reporter.

我有一个作为记者的法则。

As a rule of thumb, one can never be overdressed.

一般来说，没有人会过分打扮自己。

This basic knowledge is in most cases a rule of thumb.

这种基本知识在很多情况下是经验之谈。

A rule of thumb if you like. A way of making a decision.

拇指原则，一种做决定的方式。

He's quite untrained but he can build a greenhouse by a rule of thumb.

他没有受过什么训练，但能凭实际经验建造温室。