Instead of using your dominant hand to write the word, use your other hand. Writing with your other hand might be a little more difficult than it sounds. Using your less dominant hand forces you to concentrate on carefully forming the letters. This method is also helpful because it uses the other side of the brain, which can be beneficial to memorization.
Backwards Words is a pretty simple exercise. Begin by writing the word like normal. Next, spell it backwards. You might want to switch back and forth a few times before moving on to the next word. Spelling backwards helps you remember the relationships between the letters of a word.
Story Words is a creative way to learn words. The only requirement of this exercise is that you use all of the spelling words in a short story. This is a more natural way of learning and helps you learn the meaning for words as you use them in the context of a story.
For this exercise, choose two words that have at least one letter in common. Spell them out in such a way that they intersect at the shared letter. You can repeat this pairing for as many words as you can, or try to connect them all together. This exercise is especially helpful for tactile learners.
Rainbow Words requires three different colored pens, pencils, or markers. When spelling the word, use an alternate color for each letter. This forces you to stop after each letter and concentrate on what comes next.