1. Date of Birth
Never state your date of birth on your CV/Resume, whatever your age. It's not a requirement, and probably won't be a limiting factor anyway once you've had the chance to show-case your value to the company at a face to face interview.
2. Email address / Contact Details
People who use email accounts that were popular way back, such as Hotmail or AOL, might be perceived as older, while more recent accounts such and Gmail create an air of current and tech savvy in employers' minds. Consider switching your CV/Resume email to a Gmail account.
Don't give your age away in your email, such as firstname.lastname@example.org, as the reader will probably assume that the number is your year of birth. Instead, use a simple email naming convention such as email@example.com or firstname.lastname@example.org, without any numbers. If your chosen name convention is already taken by another user, keep trying other formats until you find one that's available.
Also, state just your mobile/cell number, not your home phone number, and consider inserting a link to your LinkedIn profile to stay current.
Important - if you state a LinkedIn profile address, ensure your LinkedIn profile is optimised and in-sync with your CV/Resume, as many employers will review your LinkedIn profile these days. If you don't have a LinkedIn profile, give serious consideration to getting one - it's free and can help open doors to job opportunities.
3. Professional Profile
Most CV's/Resume's start with a summary of experience, which can lead to age assumptions. For example, an experienced person might state: "...over 25 years Software Development experience..." A better way of stating this, without triggering any age assumptions is: "...10+ Software Development experience..." or similar.
4. Education, Awards, Training
Remove all dates. State achievements and where they were awarded, in order of highest qualification or most relevant first, but with no dates. Employers might seek to validate your awards, but dates are not usually a component of this process.
Demonstrate that you have relevant experience required for the role (employers often state X years' experience in job descriptions or imply the same), but try not to go back more than 10 years or so. You can always share earlier experienced during an interview.
Note: Some people say that you should state earlier experience if it's relevant to the job you're applying for, but few employers will take much notice of experience that long ago.
Very Important - use the right keywords because automated processes and people will scan for these keywords as an indicator of relevant experience. Use the same keywords / phrases that are stated in the 'required' part of the job ad/description, stating the most important words or phrases more than once, particularly in your most recent experience.
State only the relevant and current technical skills that are required by the job, delete irrelevant skills to bring the focus to what's relevant, and remove outdated computing skills such as WordPerfect and Lotus123 as these will trigger assumptions about your age.
Don't state your kids' age and consider not stating you have kids at all, as this might lead to age assumptions being made about you.
8. Red Flag Terminology
Avoid red flag terminology such as 'mature', 'seasoned', 'young looking', 'youthful', 'fit', 'healthy' and so on. And get a feel for the style of terminology being used in the job advert and on the employers' website and try to adapt your writing style to suit.
When you make these simple enhancements to your CV/Resume, your chances of being selected for interview will be greatly enhanced, guaranteed. I wish you prompt success in your job search and please do feel free to share your experiences.