Note that the following is going to be aimed more toward people characterised as 'shy guys' or 'a good person but not fuckable' than dudes who are regularly characterised as 'creepy' or 'coming on too strong'. The obvious stuff like 'wash, work out, dress well, stand up straight, pay attention to her body language', etc all applies even though I haven't gone into detail about it. The exact reasons why these tips work have been omitted for brevity, but the leftist explanation will generally entail saying 'socialisation' and 'lived experience' a lot, while the rightist one will be a long, droning 'biotruths'. There are tons of little tips and tricks and rules that work well but have gone unmentioned, as in practice you'll forget them entirely unless you resolve to go out and put them into practice the same day you read about them.
Above all, observe Dan Savage's 'campsite rule': leave a person in better shape than you found them. If you think something I've said below countermands that rule, I can assure you that you've misread me.
The number one mistake you see over and over again is dudes not escalating the interaction fast enough. This is the sole real basis for the 'friendzone' - the dude did not register his romantic intent in a timely manner, and was therefore assumed not to have any. Some men act as if their sexuality is an unbearable imposition, an idea that needs to be slowly introduced to an unwitting woman in order to avoid scandal and rejection. Ironically, acting like this guarantees rejection.
This tip applies to every step of the interaction - don't hang around exchanging glances, go up to her literally within 3 seconds of making eye contact. Don't leave room for Jesus between you all night, establish (respectful, consensual) physical contact. Et cetera.
Poker machines lose their compulsive effect if they always pay out. Cats stop playing with a string when you stop bouncing it around. A rollercoaster that doesn't go up and down is a train and isn't nearly as fun. A nascent romantic entanglement loses its thrill if the outcome is never in doubt.
If you're constantly pushing the interaction forward, you give the impression that there is nothing that would be a 'dealbreaker' for you. This in turn implies that you have low standards, which implies desperation, which implies that you aren't worth her time. Conversely, demonstrating that your attention and approval isn't a certainty implies the opposite about you. In other words, if your approval is free it's not worth anything. Pulling back occasionally gives the interaction some spice, makes her invest in it.
Also, if you're constantly running hot, you're only hitting the one emotional note, which quickly gets boring. An effective social interaction of any kind should hit on a range of emotional states - intimacy, sure, but also contentment, melancholy, laughter, anger, joy, fear, curiosity, etc. The wider the array of emotions you can stimulate (in a harmless way, of course), the more engaging you'll be. She'll feel like she's 'known you forever' (because you'll have a big range of emotional associations, just like people she's spent a lot of time with).
The easiest way to make a million dollars is to start with a billion. Social media sensations gain followers on the basis of their follower count. Protoplanetary bodies accrete material according to the gravitational pull of the material they already have. Women will like you if they see that lots of other women already like you.
There are two ways to make this work for you: externally and internally. In PUA terms: 'social proof' and 'abudance mentality'.
Social proof is pretty straightforward: direct proof that you're socially valued. You turned up to the club with a big mixed-gender group. You've worked the whole room at the party. The bartender's your best mate. There are women hanging off your every word. You can bring people and groups together, make introductions. All your stories start with "So I was out with me mates…". And so on.
Abundance mentality is you behaving like someone who has a lot of social proof. You'll stride confidently into a room, because you know everyone likes you. You're not going to bend over backwards (or, heaven forfend, pay) for a woman's approval - if anything, you're deciding if SHE'S worth integrating into YOUR schedule. You're not going to sweat the outcome of an interaction, either - why would you? It's not like women are in short supply. And of course, you're going to be nothing but friendly to dudes in any mixed group you approach - after all, competition implies scarcity.
This might seem like a chicken-and-egg problem, but it's quite soluble - the abundance mentality behaviours are incredibly easy to fake at range and in shallow interactions, and a quick round of 'working the room' creates enough social proof to kickstart the social proof accumulation process. As it accumulates, the need to fake abundance recedes.
There's going to be an early phase in basically every approach in which you're doing significantly more than half of the talking. The exact content of this conversation will be unimportant, but the total information imparted will make or break the interaction. You'll essentially have to indirectly demonstrate that you're interesting (Tip 2) and in demand (Tip 3). The point is, you're going to be carrying the conversation for a while, so you should get good at speaking extemporaneously. If you're not good at this, it can be convincingly faked with some well-rehearsed stories tuned for entertainment value, coupled with a bit of improv practice. In my younger years I joined Toastmasters, a public speaking club. I can recommend it, as you get the opportunity to practice both prepared and off-the-cuff speaking. Also, don't worry too much about if your chosen improv ramble topic is 'too niche/nerdy/boring', for a couple of reasons. First, if she's not feeling it you're gonna see it pretty quickly in her body language: closing off, moving away, reduced attentiveness - this will provide ample warning for you to change tack. Second, topic choice counts for very little compared to emotional content. If it's uncool but you speak passionately about it, you'll likely maintain her interest.
Reading all the books and top 5 lists in the world won't help you if you don't go outside and talk to women. A certain Go proverb comes to mind: "Lose your first hundred games as quickly as possible." I know of two ways to maximise your practice: immersion and structured (or 'deliberate') practice. For immersion, put yourself in a position where you have to interact with people. Getting a bartending job is a popular suggestion, what helped me a lot was staying in hostels when I travelled overseas. You can also try structuring your practice by setting specific, incremental goals - 'I'm going to go out 3 nights this week', 'I'm gonna introduce myself to everyone in this bar', 'I'm gonna approach 5 women tonight', etc.
Aside from all that, it should also be noted that 'it's just practice, it doesn't matter what happens' is also a pretty decent mindset to adopt when going out - from the outside, it looks exactly the same as the 'abundance mentality' of Tip 3.