EYOOOOOO, so I want to make this about the feature, 'clipping group'

But I'm really bad at explaining, SO ENJOY.

In paint tool sai, there is this feature called 'clipping group'. What's that, you may ask? WELL YOU SEE CHILDREN, LET US FIRST TALK ABOUT THE PRESERVE OPACITY FEATURE.

as you can see here, I drew a thingi (may be a bunny) 

and now for some reason, I might want to make it pink instead? Or different shades of pink. But how could I possibly do that???

Just go to the layer and check the preserve opacity box

now, you will only be able to draw/change things of the drawing in that layer you can't go outside. for an example

this is when I preseverd the opacity, notice how it's only in that one drawing? It's not outisde the lines or anything

but if I uncheck the preserve opacity box.

bam. it's outisde the drawing.

This is really useful depending on what you want to change or what you are drawing. But my favourite thing to is to use the clipping group.

So since we talked about the opacity feature, let us talk about clipping group. Clipping group works like a mask, 

you make a new layer above of the colour layer or something like that, and then you will only be able to draw what's under the clipping group layer.

Example

as you can see, I want to shade my bunny, without going outside of the drawing.

So I just make a new layer, and check the clipping group box (Note, YOUR CLIPPING GROUP LAYER MUST BE ABOVE OF THE MAIN PAINTING/THE LAYER YOU WANT TO CHANGE)

and then I start shading, as you can see, it's only inside of the bunny. 

But if I uncheck the clipping group, it will look like this.

Clipping group is very useful if you are drawing characters or animals (backgrounds are also pretty good)

I'm sorry, I told you guys I can't explain XD please comment if you have any questions

ps: I recommend that you colour in different layers! Like, hair in one layer and skin in another. that makes it easier to use clipping group

as you can see, I coloured the skin and hair in different layers.

So if i want to shade the skin

you just make another layer on top of the skin colour layer (???)

same goes with the hair