I didn't go on my first date until a month before my 30th birthday. Met my eventual wife on OKCupid 18 months later, married her 2 years after that, and now have a 7 month old, ~7 years after it all started.
I'll disagree with a lot of the advice given here. The pictures on online dating sites are what you make of them. I didn't even like my wife's pictures, I only messaged her because she was playing 4 truths and a lie on her profile and I wanted to call out the lie. I also read The Game and some PUA communities, but soured on them when a.) all my female friends told me "Dude, you're skeevy just for even mentioning them" and a married coworker was like "Well, it works on some girls - usually the type that's a total trainwreck in a relationship anyway."
Things that did work:
1. Send lots of messages, and go on lots of dates. I think I sent about 250 messages and went on 30+ first dates. Only 3 led to a second date, and the two that were not my wife were previous offline acquaintances that happened to pop up on my OKCupid matches. (I dated them for like 15 and 8 dates, respectively, before deciding that it wasn't really working.)
2. Dating is basically entirely emotional. Whatever rational thoughts you're having about it are probably useless, and probably counterproductive (other than avoiding obvious pitfalls like dating someone who's married, someone who's cheated on everyone they've always dated, someone who wants a totally different lifestyle from you, someone who wants kids when you don't, etc). Go with your gut on everything. Don't trust your gut? Work on that problem first before dating.
3. "Common wisdom" is more foolish than most people think. I had a couple coworkers take me out on a shopping makeover, where they helped me pick out some very stylish new clothes that got me complements from a bunch of my other friends. What was my eventual wife's reaction? "Well, he's cute, but I think he may be gay. Maybe I'm barking up the wrong tree here..." And then she called me SkinnyJeans to all her female friends for the next 2 months (this was 2012, it was the style then). She didn't (and doesn't) care about appearances; that was part of what makes us a good match.
4. Broaden your idea of what a good partner might look like. As a kid, I had an image of my eventual wife: thin, white, blonde, popular, gracious, and smart. My wife is the latter 3 of these, but she's a stocky Taiwanese-American. And similarly, I'm not a bald Mexican soccer player named Santiago. ;-) (Ironically, both of us previously dated people who pretty much entirely matched our checklist, and found we couldn't stand talking to them.)
5. Related to the last 2 points, you aren't looking for America's sweetheart, you're looking for your sweetheart. Our couple's counselor told us that one common failure mode for people who get married young is that they marry the image of what popular culture says they should want, which presents a lot of problems when they grow older and realize that they have preferences & values that are distinct from what the culture around them values.
6. When you meet the right person, you'll know. Well, sort of. I knew within 20 minutes of meeting my wife that she was a lot more fun and easier to talk to than any other first date I'd been on. I didn't know for sure that I wanted her to be my wife until about 6 months after we got married. Most of my objections in the intervening 3 years were fears masquerading as rational objections - "Am I really ready to settle down?", "But she's not who I thought I would marry", "It's weird having her family so close by when mine is all the way across the country", "What'll this mean for my startup dreams?".
7. Learn to recognize fear. If you want to be with someone even though you're afraid of it, you must really love them. Listen to that and not the fear. (Note that I said "it" instead of "them" - if you fear the person, that's a real problem you should listen to. Many people don't fear the person, they fear the relationship and what it means for their self-identity.)
8. Consider therapy. It's cliche, but you have to learn to love yourself before you can expect other people to love you. I was bullied pretty intensively in middle school, which included a lot of sexualized teasing of the form "I can't imagine nostrademons ever getting a girlfriend", even from my "friends". I internalized that over the next 18 years, such that even long after I'd left my home state and everyone I knew behind, I was still subconsciously living it. Once I became conscious of that thought-loop and dealt with it, it was only 3 weeks until I found my wife.