You might want to try "word families." If you aren't familiar with these, start with a stem, such as 'ow' then change the first consonant: cow, bow, brow, how, now, plow, wow. Or, use the Dolch Word List, which are the most freqently used words. Links to both of these are listed below.

Check to see if your child is able to identify letters and their sounds easily? If not consider, practicing these first. Then, consider having your child write the difficult word in a baking pan filled with sand. Ask your child to use the letter sound of each sound as he/she writes the letter into the sand, then sound all the letters out together.