Here are the concepts that were most helpful to me:

• Reduce attachment that finding a partner is going to solve your happiness and build a life others will be attracted to. Seriously. I had to accept a future of being forever alone before I could let go of the fixation and move on with my life. The misery of being single almost entirely revolves around this fixation. Focus on building a life that you would be excited to share with someone. I recommend You Are the One You Have Been Waiting For: https://tasshin.com/blog/you-are-the-one-youve-been-waiting-for/. Bonus of this: if you do not need a partner, then you will encounter less anxious attachment early on in courtship. This will help you navigate the courtship phase much more deftly. It is one of the tragedies of the world that the people who least need a romantic relationship are the ones who will have the easiest time finding one.
• Once you have built a life that is attractive to others, then increase your probability of meeting people that are in your field of eligbles and actually ask them out. Helpful summaries about this are: https://thingofthings.wordpress.com/2018/05/25/models-a-summary/ and https://colah.github.io/personal/micromarriages/. There are different strategies people have tried that basically amount to this. Date Me docs, being more strategic with OkCupid, going to parties and meetups. These are all about increasing the number of people in your proximity that are part of your field of eligibles. Video on the field of eligibles and proximity effect: 

• If you are using a dating app, then the most impactful thing you can do is invest serious time in improving your profile. This means paying attention to photos and whatever other content is part of the profile. Get feedback from people you trust. Hire a professional photographer. Do tests and see which sorts of profiles get you more responses. 
• This is controversial and more of a strong opinion I hold that others disagree with. I found that people are not actually very good at predicting what matters in a partner. I am not saying "lower your standards", but most of the things people have on their lists for desired partner feel to be missing the point. Having aligned views on the life you want to build matters quite a bit, but you might find yourself surprised by who end up being attracted to. My current nesting partner is not a nerd, adventurous, and a huge extrovert. These are traits I filtered against in the past. Focus on chemistry: are you attracted to them (sexual compatibility)? Can you understand each other (mental compatibility)? Are you aligned in the life you want to build (life compatibility)? Everything else matters a lot less (in my experience).
• The skills needed to find people in your field of eligibles are different from courtship skills. Courtship skills are different from the skills that lead to longer lasting relationships. An example is that tension and mystery can matter quite a bit in the early stages, while being very good at Needs and Boundaries matters a lot more in the later stages. Meeting someone you like and beginning the courtship phase with them is only the very beginning of the journey of a life-long partner. All of the other skills involved are beyond the scope of this post.

You might like this, which elaborates a really nice philosophy and applies it to dating.

I don't think it's central to your question, but I would discourage framing this as motivated by it being high impact. Any discomfort or life challenges whatsoever will reduce a person's productivity; that doesn't imply that all discomforts that EAs could face are top cause areas. Challenges in finding and maintaining relationships are a natural feature of life and not bugs that reduce our potential impact.

This kind of reasoning is also especially prone to motivated reasoning:

Justifying, in these cases, is also a way to get practice... in motivated reasoning. Why did you go to two parties last weekend? Maybe you just need two weekly parties to be happy enough to work. Why were you spending so much time trying to get an A in differential equations that you forgot to apply to that internship? Well, a top 5 PhD program requires a high GPA. These justifications could be true, but are they really why you did the thing?

I came across this some time ago through lesswrong - https://putanumonit.com/2016/02/03/015-dating_1/

might be what your looking for :)

Fair enough. I don't actually think it's a super high impact thing, I just needed an excuse to post it here. Otherwise would have seemed too random.

Come to think of it LessWrong would have been a better place to post.