A crossword puzzle is a battle between the puzzle maker and editor on one side and the solver on the other. But unlike most battles, both sides here have the same goal -- for the solver to win. A perfect puzzle may put up lots of resistance. It may, in fact, seem impossible at first. Ideally, though, in the end the solver should triumph and think, Oh, how clever I am!

The perfect level of difficulty, of course, differs from person to person. This is why, as editor, I vary the weekday Times crossword difficulty from easy-medium on Monday up to what the actor and puzzle aficionado Paul Sorvino calls "the bitch mother of all crosswords" on Saturday. (He said this as a compliment.) The goal is to have something for everyone. I advise new solvers to begin on Monday and see how far through the week they can go. The Sunday Times puzzle, while larger than its weekday counterpart, averages only Thursday-plus in difficulty.

Step 1 in solving any crossword is to begin with the answers you're surest of and build from there. The fill-in-the-blank clues are easy to spot and often the easiest to solve. Focus in the early stages on the three-, four-, and five-letter words, because the English language has relatively few of these, and the same ones tend to repeat a lot in puzzles. This is especially so for vowel-heavy words like ALEE, IOTA, EEL, AGO, OREO, etc. Watch for the celebrity names (UMA, ARTE, ENO, AGEE) and geographical names (ADA, AMES, ELON, ORONO) that crop up with unusual frequency. Once you have a few crossing letters in the longer answers, you'll be more likely to get them from their clues.

Don't be afraid to guess. At the same time don't be afraid to erase an answer that isn't working out. For the clue "Butcher's offering," I once watched a solver successively guess T-BONE, CHUCK and STEAK before finally hitting upon the correct answer, SHANK. Don't assume that because you have a few crossing letters that your answer is necessarily correct. And if nothing seems to cross the answer you have filled in, be very wary.

Mental flexibility is a great asset in solving crosswords. Let your mind wander. The clue "Present time" might suggest nowadays, but in a different sense it might lead to the answer yuletide. Similarly, "Life sentences" could be obit, "Inside shot" is x-ray and my all-time favorite clue, "It turns into a different story" (15 letters), results in the phrase SPIRAL STAIRCASE.

The New York Times crossword has not printed hints like "2 wds." and "3 wds." since the early 1950's, so be on your toes for multiword answers. One answer that always seems to trip solvers up is R-A-N-D-R, which was clued as "Leave time?" when it first appeared in a Times puzzle several years ago. Afterward lots of solvers called and wrote me saying that they couldn't find the word RANDR in their dictionaries, and where did I get it? I had to inform them gently that the answer was three words, R AND R, as in the time when one goes on leave.

A question mark at the end of a clue can mean several things. In the above clue for R AND R, it means "This clue is tricky! Be careful!" It can also indicate that the answer only loosely fits the clue. For example, "Cause for a head-slap?" (BONER). Making a boner may or may not be cause for slapping one's forehead. When question marks appear at the ends of the clues for all the long answers in a puzzle, usually the marks are signals for related puns.

No matter how tricky or misleading the clues, they will always follow a fairly strict set of rules. Most important, a clue and its answer will always be expressed in the same part of speech and as a rule must be interchangeable in a sentence, with the same meaning each way.

If a crossword answer is not a Standard English word, the clue will usually signal this fact. Thus, a slangy answer will have a slangy clue. The clue for an abbreviated answer will contain the tag "Abbr." or else a word that is not usually abbreviated ("Entrepreneur's deg." = M.B.A.). Similarly, words that are strictly foreign will be signaled either directly ("Boy: Sp." = NINO) or indirectly ("Son, in Sonora"). By convention, diacritical marks are ignored in American crosswords, so don't worry about that tilde in "nino."

True crossword cognoscenti observe the bylines on the crosswords and prepare themselves accordingly. Cathy Millhauser, a frequent Times constructor, is famous for puns. In a puzzle called "M-M-M" she changed N sounds to M's at the end of familiar phrases, like SAVINGS AND LOAM, AMERICA ON-LIME and AS CRAZY AS A LOOM. Knowing her tendencies helps you nail one or two of the long puns, and you have a big advantage in getting the others.

The constructor's age is sometimes reflected in a puzzle. Frances Hansen, 81, one of The Times's longest-running crossword contributors, produces elegant grids full of classical knowledge, while Brendan Emmett Quigley, 26, a guitarist for a rock band in Boston, conveys a younger, more pop-cultured sensibility.

If you get stuck on a puzzle, a time-honored technique is to put it aside and return later. Perhaps the brain works subconsciously on problems in the interim. Whatever the case, a fresh look at a tough puzzle almost always brings new answers.

A question I am asked often is this: "Is it cheating to use references?" In reply I always quote Will Weng, one of my predecessors as Times crossword editor: "It's your puzzle. Solve it any way you want." And is it cheating to call The Times's 900 number to get answers? Well, of course! But what nobody knows won't hurt you.