If you're in a real hurry to unscramble a word, use our solver (to the left). Otherwise, here are some tips to make it easier to unscramble words by hand.
First, look for opportunities to make plurals. If you see an 'S', be ready to tack it onto the end of any word you can make with the remaining letters. The same goes if you have 'ES' or 'IES'. One cool cheat with a lot of word game programs is they check for plurals using rules rather than a dictionary, so they will accept tacking an S on the end as a good word. Expect some whining on the message screen if you do that (although the move is fair).
Next, take a look for any prefixes or suffixes. These are common sequences of letters that are used by many words in the english language. They can be another quick way to unscramble words. Find your prefix or suffix and test mixing up the other letters to make more words. For puzzles, once you're sure you know the prefix or suffix of a word, you really reduce the number of possible words you can make.
Consonant patterns are another great way to go after the possible words. If you spot a "th" or a "ch" or have two consonants and a couple of vowels, start swapping the order of the vowels around to see what words you can unscramble. Once you have an idea about the rough order of your consonants, there are a very small number of ways to arrange your vowels into words - which can speed up your solution. We had this kind of thinking in mind when we designed our word scramble game.