Music/SFX
Simple tuning of your sound. Often useful after a long game, when you want to turn off annoying music. A sound can sometimes be useful to indicate what is currently happening during the painting process.

Fullscreen
Just depends on how wide the van screen you need to paint.

Mute
Completely mutes music and sound.

System cursor
Allows you to use one of the cursors. Either the cursor from the game, or the cursor installed by your device (computer).

Show tiles animation
Might be useful for weaker devices, although I'm not sure there are computers that can't handle this game.

That is, during painting, the cells appear animatedly. Or, they will simply appear instantly when painting.

Highligh tiles of the selected color
Turns off cell lighting. In general, this is just an auxiliary function for painting.

Relaxed mode
This mode makes it easier for you to paint without making mistakes. This is the easiest way to get the Scientist achievement.

Filler
It is better not to try to use it forever. Especially in XL format, because in such pictures it accumulates the longest. It is desirable to find, and even better in the process of painting, to look for certain large solid colors (illumination of the cells can help).

Blockbuster
You can use it in two moments:

• When you see a bunch of non-monotonous colors, sometimes when the rainbow pencil is not filled enough.
  
• To eliminate difficult points, not to try to paint here for various reasons. The reasons may be different, just evaluate during the dyeing process what will be easier for you and what will be more difficult.

If certain difficulties arise, you can try to ask in the comments, maybe we will help.

Ranbow Crayon
Also for various reasons:

• Filling non-monotonous spaces, often they are visible and have different shades of gray (unfilled colors).
  
• Square tactics. That is, you draw a square, and then fill/color inside it. This is very often used in the larger and more difficult drawings, which can often be found almost everywhere (episodes) as you progress. Just appreciate what the colors of the backlight show.

The process itself is very diverse. There are different episodes where the drawings are different. Here are some examples I know:
1. Somewhere there is a basic color, such as 0 or 1, which is the basis of the whole picture. And then we color everything in areas that are separated by the main color. This is roughly what is used in "Distant Worlds", and maybe also in "Spooky Rush".
2. Some points, unlike the previous point, may be different. That is, the colors are superimposed on each other, so you can try to paint at an increasing pace (1, 2, 3, 4, 5...). For example, in "New Voyager" or "Cooking Time!".
3. The episode "Spirit of Christmas" has different forms of drawings that you just have to try to get used to. I will say a little about this later in the conclusion.
4. See How to paint easily 8-Bit World?
4.1. If this drawing is small enough (in later episodes) (in promotion), then do the same in growth. In other cases, we do the same as the previous ones. At your convenience.
5. This strategy can be applied to all episodes, it only depends on the size and shape of the drawing. This can often be the case with XL sizes. To do this, you need to fill in the rainbow pencil at least a little. And then use it to color in any squares, in order to fill them in later. You can fill them in at the same increasing pace. You can see an example here in the screenshot.

In general, before starting to paint, it is worth investigating how the colors are located in the backlight. In this way, you can try one of my strategies, or do it yourself somehow. I'm just trying to explain my experience.

Also, if you want to clarify some point, share and/or combine our common experience, etc., write in the comments. I will be happy to listen to what I may not have achieved myself.