Scrabble is all about racking up as many points as possible and the high scoring tiles offer some great potential. Both the Z and Q are worth 10 points, while the J and X are worth 8 points. Finally, the K weighs in at a decent 5 points. However, finding decent sized words with these letters is not always easy. While QUARTZ and QUIZ usually pop to mind, it is not common to have both the Z and the Q, let alone also the requisite U. As noted in the article on 2 letter words, the best starting point is with the shortest words: ZA, QI, JO AX, EX, OX, XI, XU, KA and KI
The good news is that there is almost always a way to play off these letters. A word of caution is that while these high scoring tiles are great early on and during the middle of the game, they can become a bit of an albatross at the end. This is due to how the end is scored. For example if you have the Z, Q, and O left on your rack when your opponent plays his/her last tiles off, there score will increase be the amount of points from your tiles and your score will be decreased by that amount. With the Z, Q, and O this would amount to a 42 point swing. This is often enough to turn victory into defeat. Exception Scrabble players will be able to figure out what is left on your rack and often play off their final rack and count on these additional swing points to capture a win.
ADZ, AZO, BIZ, COZ, FEZ, LEZ, FIZ, LEZ, WIZ, ZAG, ZAP, ZAS, ZAX, ZED, ZEK, ZEP, ZIG, ZIN, ZIP, ZIT, ZOA, ZOO, ZUZ, ZZZ.
I have to admit playing ZZZ seems a little unlikely since it requires the Z and both blanks.
QAT, QIS, QUA, SUQ
3 Letter X Words: AXE, BOX, COX, DEX, FAX, FIX, FOX, GOX, HEX, KEX, LAX, LEX, LOX, LUX, MAX, MIX, NIX, OXO, OXY, PAX, PIX, POX, PYX, RAX, REX, SAX, SEX, SIX, SOX, TAX, TUX, VEX, VOX, WAX, XIS, ZAX
See 3 letter J words here and 3 letter K words here.