One: a summary that could describe anyone. Fix: write a summary that states the role you are targeting and one concrete signal of fit.
Two: job titles that do not match the industry. Fix: if your internal title was unusual, add the industry-standard title in brackets.
Three: dates in an inconsistent format. Fix: use Month Year – Month Year throughout. No exceptions.
Four: bullet points that describe duties, not outcomes. Fix: for every duty bullet, ask "and what did it produce?" and add that.
Five: too much education for a candidate with ten years of experience. Fix: compress education to one line once you are more than five years past graduation.
Six: a skills section that lists everything. Fix: keep eight to fifteen genuinely relevant tools and technologies.
Seven: a photo on a resume for a market that does not expect one. Fix: follow local conventions; check the region you are applying into.
Eight: fonts below 10 points or unusual decorative fonts. Fix: use a common font between 10 and 12 points.
Nine: inconsistent headings. Fix: use standard section headings throughout.
Ten: a PDF that is not selectable-text. Fix: export as selectable-text PDF, or submit DOCX if the employer allows it.
Eleven: typos. Fix: read the resume out loud, then ask someone else to read it.
Twelve: a generic file name. Fix: name the file with your name and the role. "Jordan-Lee-Product-Manager.pdf" beats "Resume.pdf".
None of these fixes take long. All of them improve the resume a recruiter sees.