Quickest way to get 50 stars in the crossword game is to use a macro tool like TinyTask.
Set the active tile as the upper left (1 Across/1 Down) and have it click the Hint button indefinitely. The Hint option will add the correct letter and the next time it is pressed (there is a 5 second cooldown per Hint) it will automatically move to the next letter/word/row.
All you have to do is wait for the crossword to fill up, stop the tool, select the next level and then start the tool up again.
It takes a while but it's far less taxing than Binging the answers on google if you aren't very good at crosswords.