You always have to be careful about what you might leave your opponent. One obvious example - you do not want to end a word immediately before a TW if that word can take one more letter (such as an S) to give your opponent the triple in two directions.
Example: you can play KNIFE for 30 points but the E would be placed just before the TW. Don’t do it. Opponent can play an S or a D for thirty-some points plus the triple value of the word he creates in the other direction. Instead, play FINK for probably 1 or 2 points less yourself.
I modify my defensiveness according to the state of the game. If I get 50+ ahead, I play defensively and clamp the board down as tight as I can. If I am behind, then I will take more risks.
Another strategy is to keep a balanced rack - not too many consonants or (worse) vowels. It is better to score 25 and leave yourself with DER than 30 and leave AAE.
The defensive strategies we’ve seen involves making short, two letter words and blocking off as much of the board as possible, cramping the board as much as possible. The letters V and C are also good for blocking, as you can’t make any two-letter words with them that are legal in WWF.
We like a wide-open board that permits a lot of play, and will set up opponents with triple word letters and such to open up the board, but that’s because we’re stronger than most opponents.
Know your high value two letter words: QI, JO, ZA, AX, XI, OX. Even when your opponent is opting for a tight defensive game, you can often get big points from them. Frex, suppose you have the word TAME with a double letter above the A. If you play ZA above it with the Z in the double letter, you get over 40 points because the Z is a double letter and it’s used twice.
Don’t hesitate to swap tiles out if you have a really unplayable rack. If you’ve got four Is and three Vs, you’re screwed anyway, barring some unusual setup on the board, so swap and move on.
Look for words you can make by adding to the beginning rather than the end of a word, because it’s easy to forget about that … like adding a C to Left to make Cleft.
We also will play words just because we like them, and will avoid playing words that most folks don’t know. Szygy is just hard to explain.
And beware of opportunities to let the opponent score big on the triples. If it is near the end and the Z is still out and likely in your opponent’s rack, don’t play an A east or south of a TL that could allow your opponent to play ZA both ways and score 62.
Unlike Scrabble, WWF allows you to get a TL and TW in the same go. J, Q or Z on the TL in a TW scores 90 points for that letter alone. If I am considering leaving a TW available, I pay particular attention to the nearby TL. Best is if I take it. Next best is if it is hard for the opponent to put a high scoring letter on it. For example, it is generally easier to put a high scoring letter on the TL if the next letter is a vowel rather than a consonant.