Well, it's not like you need to approach Orin and Utsuho much differently than the average forward-focus shot, just that you need to survive longer than one. :V
Midboss-Orin is "straightforward" at least, stay midway between Orin and the bottom for the first nonspell, read the bullet layouts before they move for the second, and follow her around between the Catwalk's waves (do so higher up so the homing shots have a better chance of hitting).
Boss-Orin's first nonspell is merely a case of reading bullets of two speeds - the lanes are simple to weave through (do this no more than twice per wave), so just make sure no pellets are nearby. Possessed Fairy requires side-to-side herding for someone as weak as ReimuB, and I would suggest Kefit's perfect Stage 5 Lunatic as a demo (again, only real difference is how long it takes to kill the attack).
There's a handy trick for the second nonspell that trivializes it. Stay just beneath Orin, like you're shotgunning her, and since bullets don't spawn within a certain distance from you, no bullets will appear and you only need to dodge the wisps' shots (a simple tap down). If you do this, don't forget to make sure you get back close to Orin before the next wave appears. Vengeful Cannibal Spirit can be made a lot easier by making sure the wheels spawn in the same place each time. Once again I'll refer to Kefit's vid.
The third nonspell is where things kick up a notch. It may be a randomly-oriented static pattern, but finding your preferred place to dodge stuff can feel weird at times. I usually see people go around only the bullets that close in on the open space (those superplays from Royalflare are a good example). The Ghost Wheels is tough even when you know what you're doing, so don't feel bad about that one. :V The main thing to know is that the wheels of wisps are aimed, and it's advised that you learn how far to either side you have to go to dodge them. The caveat of course is dodging the (somewhat tightly spaced) smaller bullets, a case of "read ahead". Another potential problem is keeping track of where you were when each wave of wheels spawns, which is something you'll only become more familiar with in time. Finally, Small Demon's Revival takes multiple trips around the screen for ReimuB. Start under Orin and move up toward her when the fairies approach you. Choose a couple of positions above Orin to sit for a moment, and once the fairies follow you up there carefully circle back under Orin. Repeat the luring and circling process once the fairies get too close to you.
Utsuho's first nonspell is really simple, just read where the openings are. For Uncontainable Nuclear Reaction, I prefer to misdirect the first set of suns away from the center. Stay under Utsuho at the start, but when the "charge up" sound goes off (the same time as the third siren sound), move left until you're above the CG multiplier (the "x.xx" part). Dodging the blue bullets is honestly just a case of reading ahead. Don't be afraid to go the other way from where you normally do, just make sure both suns in each wave are going the same way.
You know the space above where the bullets spawn in the second nonspell? That's technically a safespot when Utsuho is offscreen. Go there if you wish (you can reach it from just below the spot where Utsuho goes offscreen), though you can also take advantage of any large spaces you find if you play it normally. Whichever way you tackle it, you need to stream the bubbles the same way: go right the first time, then left, then repeat if necessary. Peta Flare is really all read-and-dodge. Try to stay in as open a space as possible, even if it means going halfway across the screen, and only try to fit in between suns when absolutely necessary.
The third nonspell is static. You can do the first wave at the very bottom underneath Utsuho, but for the rest I recommend learning where the open spots are in relation to Utsuho (keep in mind her height changes, so adjust accordingly). Do I even need to mention Ten Evil Stars? Use the safebox.
The fourth nonspell is easier than the second. You can actually sit at the bottom-center between two of the rows of bullets, and nothing else will come closer. The pattern for streaming the bubbles is reversed this time: left, right, left, etc. For Hell's Tokamak, I suggest staying to one side where there's more space, and where one set of bullets will be moving near vertically. Don't try to move a whole lot to either side, since Utsuho will be kind enough to stay near your shots. Finally, Subterranean Sun has that gravity gimmick. The red bullets have a similar pattern in their progression, so use that to judge where to move. As for the smaller "fallout" bullets, just stay in as open a space as possible (taking into account the red bullets of course). However, Reimu is blessed with a small hitbox, so she can still fit through some amazingly tight spaces in a pinch.
I hope I covered everything well enough.
