My best writing tip would be to read books on writing and to then just continue to write until you develop your own voice and style. Write about things that are interesting and exciting to you. I really loved some of these writing books like Shawn Coyne's The Story Grid and all of the free resources he gives out on his website.
Don't give up and don't let others get you down. Personally I think it's ok to use some help of writing services. I often use writing service help to write a paper for me and save my time. They always help me with my writings. These guys helped me with grammar and plagiarism check. Luckily they have affordable prices and I think it's ok to use a little pro help from time to time.