The other answer and comments miss the point. There are many ways to determine age, gender, and heritage that have nothing to do with stating something like “I am a black woman who is 55.” Plenty of other info can reveal it.
The other answers are also mostly from the perspective of developers. I can apply for a couple jobs and have interviews in a week, as can a lot of the people on here. Work is more scarce for other fields.
Gender
- Don’t put any gender specific activism on your resume as volunteering
- Use a gender neutral short form of your name. “Sam” over “Samantha”
- Try to fill in one year long gaps with something (if you quit to take maternity leave or something).
Age
- Don’t put your graduation dates on your resume.
- Don’t include all the jobs going back to the beginning.
- Use a less stuffy and traditional resume and one which has a little bit of colour (not a lot, but perhaps a blue dividing line instead of black). Also use a nice template.
Heritage
- Can’t do much about your last name unless you change it
- Avoid listing languages if they are not relevant to the position. Saying you know Farsi pegs you as Iranian. Urdu as Pakistani.
- Drop job locations from your resume.
- Have a native speaker of your location proofread it and add the appropriate local names for things and check for unusual word choices.
This advice is most applicable to USA/Canada.