Your resume must be carefully designed to convey a professional image. If possible, have the envelope match the paper. Use a word processor to produce your resume and cover letter. Do not handwrite changes on either form. Proofread your resume for any spelling and grammatical errors.
Typographical errors are an instant turn-off.
Have a friend with a critical eye proofread. Be consistent with your fonts, color scheme, and general page layout. Send an original resume, not a photocopy. The final piece of your resume is the cover letter. This document must be concise and quickly capture the recruiter's attention.