CV Stuff:
You say your CV is all over the place? From the short (incomplete) description you've given, IMO, your CV is nothing of the sort. In fact, if you can see it from another angle: it's all writing-related. It's scope is its strength. Essentially, you're multidisciplinary writer -- which makes you a valuable asset. Granted, the right company needs to be hiring.
Also, consider fine-combing your CV for anything that might look anomalous. Example: you're going for a tech writing job in the electronics industry. CV states that preferred industries are: "entertainment, electronics, movies, publishing, radio, and IT". As an interviewer specialising in the electronics market (which I was for a long while, at one point), I'll be asking: "Why do entertainment, movies, radio, and publishing require a tech writer? And exactly what would a tech writer do in those sectors? Doesn't make sense." If the answer provided makes no sense to me, I'll be leaning towards rejecting the candidate. (This is based on experience; I've changed the industries and job title 'cos of confidentiality, etc.)
I wonder, too, how the CV is presented? Is there a logical flow of progression? Has each position / contract elaborated on, and enhanced, the previous one? Or is it more of the same? Did the candidate use different descriptions, or was it all copy & paste then add a bit (this last is also based on experience)? How has the candidate progressed from one job to the next, how have they improved themselves along the way?
You see, what I'd be looking for here, regardless of age, is how has this multidisciplinary writing experience contributed to your career in writing? Oh, not the "apprentice to director" thing. IME, it's more a, "how does this cumulative experience show how you've continued to move forward regardless of the path you took?" Example: my own CV is very multidisciplinary. But I landed my current position because of this diversity: I'm very fortunate to have end-user experience and manufacturing experience, which are essential for my role (I'm a "translator / mediator" of sorts). And I'm closer to 50 than 20-something.
Attitude and presentation:
From experience (lots of interviewing experience here from both sides of the table), I can say that anyone who presents a persona when they interview comes across as false, regardless of how much it's hidden. OTOH, you're expected to embellish a tiny bit. Yes, interview experts say you should emphasize to the potential employer the traits that fit their ideal employee. But that can backfire if not done in moderation and at the right time, e.g., if you get to the point where you feel the next words you say are going to be too much, then they're going to be too much. Stop and let the interviewer fill in the silence.
The other thing here, obviously, is culture. Not how you think you'll fit into the corporate culture ('cos you will), but from the interviewer's perspective: do they believe you can fit in? Can you aclimmatise immediately (aka, within a month), or at least faster than the younger candidate? Can you beat the younger candidate on energy, passion, etc.? Energy, perhaps not, but can you show you have that drive to go beyond what's asked of you, to take on responsibility that doesn't necessarily fit your job description? Are you willing to do that? And can you take criticism? (The writing world, especially AW, is very kind, and go for "critique", but the rest of the world? Not at all. Not saying you can't take it, but, how do you deal with it? Because that will come across in the interview.)
And the one fear that interviewers always have which they'll never share: if they hire you, are they hiring their replacement? If they believe they are, they will fail your interview -- nothing to do with you; it's all about them.
A big question that an interviewer has is: just how flexible is your mentality and attitude? Something not many people realise: Just because they use a certain persona in the interview, there are so many little giveaways that tell the interviewer exactly how untractable or not they are, ow how much the candidate will dig their heels in or not, etc. Is that something you might want to take a look at? Nothing to do with your experience, or wealth of knowledge. It's all in the verbal and non-verbal presentation.
You could be the world's greatest writer, but if you can't express yourself appropriately verbally and non-verbally, the interviewer won't hire you.
Non-verbal communication? Body language. What's your body language when you go in? What's your facial expression when you greet the receptionist? What's your attitude / vibe when you greet the HR person? Or anyone else for that matter? The interviewer also interviews everyone you've interacted with. What's your online profile, LinkedIn? Seriously, I've done the LinkedIn search, social media search, forum search, etc., on candidates -- I wanted to know who I was interviewing and wanted a sense of who they are in a casual setting (one I certainly wouldn't be guaranteed to get in the interview).
Presenting examples / work:
You might want to check how you're presenting examples / your portfolio. Straight to the point? Too much waffle, or too much information? Directly relevant? Distantly related?
Caveats:
Just because you say the right thing, present everything perfectly, and give the right vibes / attitude, ultimately the interviewer calls the shots on whether you passed or not. And it has everything to do with whether or not the company is the right environment for you.
Last piece of advice:
I'm sure the pros have already mentioned this to you, but it's worth emphasising: interview yourself in the mirror, or video-tape yourself. You'll be able to pick up the things that would potentially prejudice the interviewer against you (age notwithstanding).
Also, record yourself and play it back -- this one is a huge one. It'll reveal any tone / pitch / inflection / etc., that may be putting off the interviewer.
Possible job options to consider:
I keep asking this, but it's still relevant: Can you work for overseas companies? You don't have to travel -- long distance freelancing can be profitable and the hours may suit you better, too. Pay? Caveats apply.
How about an English language tutor, especially for non-native speakers of English -- ESL. Tutoring, if you're in the right area or have the right contacts (think six degrees), may or may not need a qualification. Obviously, check that out before you start tutoring. Also, if tutoring young kids, you may need to a certification from the police to just certify you're an upstanding, law-abiding citizen -- this mayn't apply, but again, research is needed.
Guest lecturer / tutor at a university? College? High school? Junior school?
Hope some of this helps. Good luck!