First, practice your spelling. Have friends and family quiz you on difficult words or words that you may have problems with. Make a list of words that you feel that you have a difficult time writing and spelling and practice often.
Make sure your grammar is right. Grammar is a very important aspect when writing.
Carry a dictionary with you. Many writers find it very helpful to read a dictionary whenever they have a chance. Carrying a dictionary around is also helpful so you can look up a word that you may not know how to spell
Write sentences often. Practice writing using a lot of punctuation an grammar will help improve your writing skills. Write many sentences about things around the house, family members, or things that you are doing.
Carry a notebook and pen with you wherever you go. A small sized notebook for your purse or pocket is an excellent way to practice writing. By carrying around a notebook you can write down things that you may think of.