There are many good answers, like Vipassana, Dzongchen, even Yoga - any of derivatives of Upanishads and Buddha's insights. The problems is that for most people it means nothing, or just a mythology, so they dismiss it with a first mention.
This could be rationalized, because, like it is with every "good idea" in the world, "other people" piled up such mountains of nonsense, and pushed that nonsense using the best manipulative techniques available to humanity, that some people developed an aversion, like for ads. You could think of teachings of various prophets or programming paradigms, economics or even physics and medicine - crowds of idiots ruined and discredited everything.
The essence of most of eastern "spiritual traditions" is remarkably straightforward - "stay alone and use your own brain". It is that simple. The difference is only in wording . Some traditions call it "primordial awareness", some call it "our true nature", others call it "god within" or "That" or "Tao" - it is not important. Like they said "Truth is one (it points back to us - to "our nature") the wise call it by different names".
So, stay alone and use (develop) your own brain. It doesn't mean some radical bullshit like going in a desert. Rather it is more like Kerouac's "On the road", which is about being an observer of what is. Kerouac, by the way, didn't get Buddhism - he mere confused himself with that popular Tibetan folklore, but he was intuitive practitioner.
Another example could be like this - stop reading all that nonsense in internet - blogs, forums, HN and do read one or two great books, like SICP or PAIP or watch a serious course, like CS61A on youtube. These courses and books are for developing your own understanding of fundamental principles. Then you would see what piles of nonsense are 99% of these internet postings.
So, the answer is not go to Vipassana retreat (btw, "retreat" means solitude (to avoid distractions), so all these groups is mere business) or to turn off all the electronic devices. It means to stop paying attention to blah-blah-blah around you (that's why ancient sages went to forests or mountains) and develop yourself.
Basically, it is about using (focus) your own awareness the way children before age of 4-5 do, before their minds would be polluted by piles of words and artificial, wrong concepts they learn from others. This ability of "direct observation and knowledge extraction" which is the very essence of so-called "our human nature" is, roughly, what they worship in Dzongchen.
All the answers are thousands years old.
Oh, by the way, two-three weeks in a solitude easy trekking in Nepal (Annapurna Circuit trek or Jiri-Gokyo trek) makes wonders. You could "realize" how good it is to be alone most of the time.