The most effective tool against poor spelling is the writer's own attention. Electronic spellcheckers can easily be fooled and the writer may not notice mistakes until too late. In all modern languages, especially English, the rules of spelling have exceptions.
For a certain word with difficult spelling, it helps to make a sentence where each word, in order, begins with a letter of that word. For example: if the word "physical" is difficult to spell, remembering a sentence such as "Please Have Your Strawberry Ice Cream And Lollipops" can help the writer to remember the spelling. The first letters of all the words, when put together, spell "physical." Sentences that are fun and goofy are easier to remember.
Another tip is to create memory aids to distinguish between two words of similar spelling. For instance, with the often-confused words "desert" and "dessert," remembering that one always wants second on dessert helps to remind the writer that "dessert" has a second "s."
Additionally, it helps to sound out difficult words aloud slowly. Spelling bees bring out the best spelling skills in children because they encourage good listening; hearing the word spoken by a second party may increase the understanding of the word. Finally, there is no better tool for memory building than repetition.