Youmu:

> "I mean, he's a businessman, right? He wouldn't give you something for free, I imagine."

Myon:

> Shrug again.
> Step back outside the shrine and open the box.

> Maintain a stern look to ensure the fairies don't try some kind of underhanded trick!  Summon the orb to spin above our palm for emphasis.

> Has anyone's 'aura' changed?

> None have.
> You summon the orb form for a more physical threat.
> "Why are you still so tense? Do you wanna take on my tower?" Cirno accuses.
> "They were just trying to settle the dispute moments ago, Cirno.." The other fairy says.
> "That doesn't mean they're not trying to get it for thrmselves."
>_

I've made assumptions on some parts here, I'll label them in italic.

I've had some calculations on Marisa's Master Spark, what width and what height it is.

Let's say Marisa's height is 130cm, because I saw the in-game character and pixels on some games look fairly short.

Let's say the play area is 600x800. (If we assume that  the play area is 3:4 aspect ratio.)

Let's say the Master Spark covers roughly 85~90% if the play area.


Calculations:

Height of the Master Spark:
Minimum: 130cm * 0.85 = 110.5cm
Maximum: 130cm * 0.90 = 117cm

Width of the Master Spark:
Minimum: 110.5cm * (4/3) = 147.33cm
Maximum: 117cm * (4/3) = 156cm

So minimum height and the maximum height
is roughly 110.5 to 117cm, and the minimum and the maximum width is 147.33cm and 156cm.

This is only my hypothesis so feel free to do your own!

> "If you could write some numbers down for me as I go, that would be appreciated. Don't worry about the math, I'll take care of that afterward."

Suspicious Person already covered almost everything possible, very eloquently as well.
I want to make mention of a Technique calls "Streaming".
Some bullet patterns are simply a lot of bullets being shot at your current position. You can dodge them easily by "Streaming", that is, moving slightly in one direction when the current flow of bullets gets near. This can free up a lot of focus and energy for truly difficult patterns.
For Example: Touhou 6: Embodiment of Scarlet Devil starts Stage 1 with Fairies shooting directly at you. Just Stream and you're fine.
For a more interesting example: Stage 4 in EoSD looks very complicated and intense... Until you notice that multiple patterns are just enemies shooting bullets at your position from different angles than normal (Below and from left and right. Rather than above). When you notice that, it becomes a cinch. ZUN like to disguise these kinds of patterns to make them look more intimidating, but they exist.

I'm also going to link This general guide with extra advice from the old version of MoTK and This Scoring Guide from our current Boss, Karisa.

EDIT: Pfft, Williewillus already made mention of it. You should watch his Touhoufest Panel in addition