5 common mistakes to avoid when writing a resume include: 1) Keeping the resume short and focused on only relevant information rather than pages long. 2) Including irrelevant work experience that is not applicable to the job being applied for. 3) Having a generic objective rather than tailoring it to the specific company and job. 4) Stating achievements and accomplishments vaguely rather than with specific details. 5) Straying from basic formatting, including proper font, avoiding complex words, and fixing grammatical errors.