You really should know all the two letter words (96) if you are going to play Scrabble. And don't think you're even close to good (I'm not) until you know all the three- and four- letter words too. And AIENERT is an important stem.
People get indignant in Scrabble when you play a word, they challenge it, and you have no clue what it means. They get even madder when you admit you are gambling on the word. Here are some words that came up in my game. I won't say who played what.
AA, AG, SH, HM