If all the players in the game decide to pass two times in a row, then it is advisable to end the game and start afresh. For the first player, it is a rule that the player should place at minimum two tiles on the star at the center. This has to be done either vertically or horizontally.
Each time a player forms a word, the player counts the score and announces it before taking tiles from the bag to replace the used ones. You will notice that as the game is nearing its end, the tiles may not be enough for each player to get seven tiles at once.
After a player forms a word, it is likely that some players will challenge the words formed. The player who has made the play should look up the word it the dictionary or resource material for the game and if the word is not allowed, the player must remove the tiles and get a zero score. Otherwise, if the word is right, then game play continues normally. In tournaments, the rules are stricter because challenging another player unsuccessfully, attracts penalties.