There is ageism, yes, but I think a deeper problem is reaction to peoples appearance. If you are late twenties concerned about age, then hide it, starting now.
* Always wear sunscreen when you are outside, regardless of race. It prevents skin aging, and you'll still tan and get Vitamin D regardless.
* Work out: lifting weights and doing cardio have differing goals and match up in interesting ways. Learn them. I do almost 100% pure heavy weight lifting, and I'm actually very thin, despite what I toss around.
* Make sure your clothes fit and look good. Go to a tailor and get one outfit made nice a year for interviews/on-sites (if working remotely) etc.
Taking care of yourself physically might not seem related to a lot of this, but people discriminate in a number of ways, and the more you take away, the better you might do. In addition, two of the above are general health things that you should be doing anyhow.
I forgot about interpersonal skills when I first finished writing this:
* Practice getting people talking about themselves. It's the best way to get people to think that you are interesting. I would argue it's the most important tool in my interpersonal skillset and I've met a ton of interesting people using it.