Find the clean set
Start with the most literal category. It is usually easier than the spelling or phrase-based groups.
Rules
Make four groups of four.
Every puzzle has 16 words and 4 hidden categories. Select four words, submit, and keep going until all groups are solved.
Watch for prefixes
Some answers share a word that comes before them, such as moon, paper, home, or cross.
Save close calls
A one-away message means three words matched the same group. Swap the weakest word and try again.