But also read your work through for mistakes. You will probably find mistakes by reading that the spell check misses. Learn that if you have not spelt a word right, you should correct it and remember the spelling for the next time you use the word. Make good use of the dictionary, read different materials now and then, like newspapers, and always read through your work. Read a lot of books and consult the dictionary.
Regular reading helps improve spelling.
Your spelling should automatically improve the more books, articles, writing you read. My spelling is poor until spell checked, but the more I read the more I see how words are formed. I regularly attend the library and really love reading. I also read a newspaper regularly, but not a broadsheet as they are very boring. I think that if people do not enjoy reading they will never be in control of their written skills, not to the potential they would like anyway.