@Eric V,
I would suggest what worked when I was doing the personals back in the day - quality and quantity, combined.
Quality - make your profile as great as it can be. This means positive language, it means completeness, and it means as good a recent picture as you can get. Have a friend take several pictures - as in at least 20 - and start to figure out your best side, that sort of thing. Positive language means you don't lie but you also don't couch things in negative terms, e. g. saying
"I don't like women who smoke." can be replaced with
"I like women who don't smoke." or
"I prefer non-smokers." It's subtle but people will pick up on it. You want to show you're a positive, friendly person, and too many negatives in a profile will contradict that.
Quantity - know your absolute requirements and reply to a set number of people who fit your criteria every week (or day, if appropriate). At the time, I was 25 so the age range I was looking for was 20 - 35. I would still consider a profile if the age was not mentioned, but if an age was mentioned and it fit in my wheelhouse, I was more likely to respond to that profile. I used to contact 10 - 20 profiles/week - and I'm a woman, which means I was more likely to get responses. And I did. I often had more responses than I could handle. Men, particularly older men, will have fewer responses, which is why you need to play a numbers game. Don't respond to everyone, but do respond to more women than you think you need to.