Everyone can improve their writing skills. Here are some great exercises online which will help you choose better words when you write, so your writing is much more effective. Some of them require Flash though, so if you don’t have it they may not work on your computer.
This Australian site has an exercise called The Sea Cave. It takes a few minutes to load so you have to be patient, but it will help you choose better verbs and adverbs:
There’s another version of the Sea Cave story here, and this time you improve nouns and adjectives:
This similar exercise has you editing a comic strip about a bushfire to improve the characters and the ending (again, it takes a while to load but it’s worth it). There’s audio if you have headphones:
This one has you rewriting a rocket trip to the moon to make it more interesting, so it helps you with how to improve your descriptive ability: