This is what Google say - "Optimizing for RankBrain (name of Google's search engine) is actually super easy, and it is something we’ve probably been saying for fifteen years now, is – and the recommendation is – to write in natural language. Try to write content that sounds human. If you try to write like a machine then RankBrain will just get confused and probably just pushes you back.
But if you have a content site, try to read out some of your articles or whatever you wrote, and ask people whether it sounds natural. If it sounds conversational, if it sounds like natural language that we would use in your day to day life, then sure, you are optimized for RankBrain. If it doesn’t, then you are 'un-optimized'."