Start with the easy ones
Spend the first fifteen seconds on short, obvious words. They are quick points, and they teach you where the vowels and common letters are. Vowel-heavy corners and clusters such as ING, ER, ED and ES are where most words begin and end.
Extend rather than restart
When you find a word, ask what it grows into. TRAIN becomes TRAINS or TRAINED, and each longer form scores more than the short one. Plurals, -ED, -ER and -ING are the cheapest upgrades on any board.
Hunt one long word on purpose
An eight-letter word is worth 11 points, as much as eleven short words. If a board shows a promising run of letters, spend ten seconds testing it. Common words, plurals and verb forms count, so think about everyday words before rare ones.
Use the Qu tile properly
The Qu tile is two letters on one tile, which makes it unusually efficient: QUIT, QUIET and QUEST all use fewer tiles than their length suggests. Look for U-less Q words only when you have the tile; you cannot split it.
Use the missed words afterwards
When the round ends, the page lists the longest words you missed. Compare them with your own search to see which patterns you overlook. Practice boards are unlimited, and each round lasts 90 seconds, so a few rounds a day is enough to improve.