etymology - How to tell if a word is Sino-Japanese or Yamato

How can I tell if a word is Sino-Japanese (漢語), or Yamato (和語)?

An answer to How 「えい」 should be pronounced in the words like 英語, 先生, etc? talks about the pronunciation of Sino-Japanese words and Yamato words.

For example, how could I tell whether 先生 was Sino-Japanese or Yamato?