The first step to helping your child become a better speller is to dedicate yourself to helping him/her improve, which you already have done! Now you need to truly think about how your child learns best, and which teaching strategies would prove most effective.
Is there a pattern in how your child misspells? Does he/she write words phonetically as they sound? Does he or she understanding different concepts about spelling patterns in the English language? (like words ending in "tion" are nouns, 'i' before 'e' except after 'c,' etc.) The article "Helping Children Make Progress in Spelling" explains that children need guidance discovering spelling patterns, and they need to memorize the spelling of words. It provides strategies for how to teach spelling to kids at each level of development. http://www.education.com/reference/article/helping-children-progress-spelling/
One of the best ways to help your child become a master speller is reading. Reading independently and together gives your kid great exposure to new vocabulary and correct spelling. Encouraging your child to read often will also prove beneficial for his/her success in all classes! Also, encouraging him/her to use a dictionary when completing school assignments can also be of help.
I hope you find the worksheets and articles helpful! Best of luck working on spelling together!
Spelling can be such a challenge! I'm a homeschooling mother to four children, and my eldest really struggles with spelling. I tried spelling lists, spelling quizzes, spelling games, worksheets, and more. She just got frustrated.
I finally decided to go back to some basics, and it has worked wonders. We spent some time reviewing phonics, and then got her the Reading Eggs program.
Although primarily geared for the ongoing development of reading skills (through age 13), it presented the materials in such an engaging manner that my daughter became inspired to spend more time reading. Her spelling improved as a natural byproduct of all that extra reading time.
I also picked up a spelling curriculum entitled, "Spelling Workout" by Modern Curriculum Press that reinforces spelling rules and encourages practice through a number of different games.
You can get a free trial of Reading Eggs from http://readingmadeeasy.org. The Spelling book is available from www.christianbook.com.