1) Continuing to practice, and by that I mean directly seeing things arise and vanish on their own over there, however you can do that. Noting is good, direct observation of all the complexity is better, though using noting to ease into difficult patterns of sensations can be useful.
2) Going wide and through: as third is more spacious, more about dissolving a significant chunk of what seems to be observing, doing, controlling, analyzing, and the like, you both have to take on more of the sensations that seem to be all of that, which they aren't, and also see how to dissolve the artificial boundaries that seem to delineate that from everything else, meaning the rest of what happens in what seems to be space. Play on that line: how do you know what the edge between what seems to be you and not you is, viscerally, perceptually, vibrationally, texturally, geographically, volumetrically? Any quality that you notice seems to really feel like it means it is you, see the Three Characteristics of that.
3) Dismiss ideals and the patterns of ideals about what you think this stuff will do as more sensations to observe. If you can do this at the level of fluxing, shifting patterns of suchness, that is easier, but whatever level you find yourself at is the level that you can work with, as it is all the same from that point of view, and knowing that simple fact can help a lot.
4) Really allow the thing to show itself. Really allow luminosity to show itself. Really allow things to just happen as they do. Less control, more direct understanding of that natural unfolding, more noticing how the sense of control occurs at all, what it feels like, how that set of textures and intentions set up a sense that there is a you that is doing anything and how obviously wrong that is. Feel into what seems to be looking, asking, wanting, expecting and vipassanize all of that: not forcefully but skillfully, subtly coaxing those patterns into the light of awareness that sees through their clever tricks, almost like you have to look just slightly to the side of the Pleiades to see them as clearly, almost as if you have to sneak up on them so gently that they don't notice it and can be caught unawares, except that sneaking process is what you are trying to sneak up on.
5) Notice that you can't do anything other than what happens. Try. See how those patterns occur. Try to do something other than what happens. It is preposterous, but when you try it, there are patterns that arise, patterns of illusion, patterns of pretending, patterns that if you start to look at them you will see are ludicrous, laughable, like a kid's fantasies, and yet that is how you believe you are controlling things, so try again and again to do something other than what occurs and watch those patterns of confusion and pretending to be in control that arise and you will learn something. This is an unusually profound point.
6) Really, really keep the Three Characteristics in all their profundity as the Gold Standards for whether or not you are perceiving things clearly, and each moment you aren't, notice why and debunk that right there, and then do it again and again and again, as it always takes more repetitions of that process than people think it should, and so many get psyched out, when it may have not been that many more iterations of the process to have succeeded in locking that in as the way of perceiving things permanently.
7) Feel the going out into new territory with its confusion, tedium, frustration and creepiness as the thing itself: that which wants it to be known, mapped, predictable, safe, familiar is part of the thing that you need to see as it is: see those patterns in the head, chest, stomach, throat, etc. as more shifting, fresh patterns: that freshness keeps you honest, keeps you really paying attention in that slightly violating, slightly personally-taboo way that really helps in the end.
8) If you are familiar with the vipassana jhanas as living, familiar, felt things, then realize that Third has elements of the Third Jhana, wide but somehow there is something creepy about it, as it violates the center in a more full-time way than the earlier paths do. The more you have a tolerance for something in that letting go through-to-the-bone creepiness and can see the good side in that, the width, the spaciousness, the naturalness, the directness, the completeness, the fullness, the now-ness of it, the better you will do. It is a more sophisticated way of perceiving things, more out of control, more brave, more free, requiring more trust, more openness, more acceptance, being more down to earth and also more diffuse at the same time, which is an odd juxtaposition of feelings to get used to, but it is worth it.
9) If you have 5th, or even 4j.5j, meaning the spacious aspect of 4th that is not truly formless but still quite open and wide, that is a really good pointer, just allow it to also go through anything you think is you, working on that seeming boundary line, as above, but allowing it to breathe, to flux, volumetrically, like moving blobs of space with texture all together, all of them just the natural world doing its rich and empty thing.
Basically daydreaming about likes and dislikes and the natural effect of emotions and chemicals released based on them feels like a separate self. Thoughts pretend to do things the body is doing (including to pretend to be consciousness).
