My rules are to start with a word that has not appeared before, selecting a word with letters that are statistically more frequently present in English words than other letters like X and Q, then follow on with words not containing letters already found to be wrong, avoiding words with letters repeated until left with no option.
I have made a 'mistake' on only a couple of occasions, yet my average is very low among the list of daily players, and I have had several 7 point fails.