Engage your readers with properly written, coherent writing. Present yourself in the best possible light when applying to new jobs.
As a native English speaker and the son of two English teachers, I've had grammar and composition hammered into me almost since birth. It's a fact of life that no matter how smart you actually are, writing properly will always make you sound smarter. Put your best foot forward and make your job application stand out with a well written, proofread resume and cover letter.
Even a small mistake could cost you an interview! For just $5 I'll ensure that that doesn't happen.
NOTE: Maximum 1500 words combined resume and cover letter. Honestly though, if your resume and cover letter are longer than that, you should rethink your strategy in general. Nobody's going to read that much on an application.