Grades on HW1 were fairly good. However, please note that I graded it more easily because it is the first assignment. Some general notes.
Use spelling and grammar checkers. Although grammar checkers are not perfect, they can be a big help if American English is not your first language, or if you never really liked writing. It will help catch lots of small errors like agreement. Small errors annoy native readers and unnecessarily lower your grade.
Read it aloud! Even fluent speakers often write poorly. But when they read aloud what they have written, they notice the problem. Written English is more formal, but should be smooth and clear.
Be Simple and Clear. Business and bureaucratic language often tries to sound important. Don't. Be simple, clear, and direct. Read about Lanhamizing your writing.