Passing the Level
Your first goal is to spell out enough words for your gopher at the bottom of the screen to reach the carrot. If you don't reach the carrot, you lose the level, so this is your first priority. Spell out as many words as you can, and if an "S" is available make words you've spelled out plural to create a new word. Type the words instead of clicking the gophers; it's much faster and saves precious time. Press the spacebar to scramble the letters when you're stuck. You can click the "Hint" button, and the game will show you the first letter of a word you haven't made yet, but it costs 10 seconds of your time.
The signs near the top of the screen show the words you've made and how many words are left. You can see how many letters are in the words you're missing. If you're missing a lot of three-letter words, for example, concentrate on those. Aim for the six-letter word if you can find it. This earns you bonus points and an acorn. Collect 10 acorns, and you get a bonus round to earn extra points and super acorns. Try reading the words you've made backward for hints to new words. "Rat" for example is "tar" backward, and if you have an "S" you can make "rat, rats, tar, star" all from the same group of letters.
Earning Bonus Points
After you've reached the carrot, you've passed the level, but you can keep spelling words until time runs out. Get a few more words, and you'll reach a blue crystal. The crystal makes certain letters appear on the signs that show which words you haven't guessed. Look at the signs and try to figure out what the missing words are based on the letters the game has filled in for you. If you don't know, find one that shows you what the first letter is and then keep trying random combinations until you get it. If any of the partially filled-in words are golden, aim for those first. Golden words give you 20 seconds of extra time. If you get every word in the level, you'll reach the bonus radish worth 50 extra points.
Operating the Drill
After the level is over, you'll want to go to the drill and see if you can advance to the next level. Certain levels give you red letters on gears. Put these gears in order to spell out a four-letter word. If you can spell a four-letter word from the gears you've collected, the drill will spring to life and drill its way to the next level. You may have to play a level several times to get enough gears to operate the drill, especially later in the game when you'll need five-letter words instead of four. If you can't get the drill to work, try playing earlier levels repeatedly until you get more gears.