Tips for sai tools

1) Use preserve tool for things like fullbody colour layers so you dont go outside your lineart / if you wanted to colour ur black lineart without ruining the original lineart c:
2) Clipping tool is good for things like textures because then you can clip it to the body of your character while without having to delete outside parts so you dont need to keep copy pasting it from the original source cos you ruined the one your working on
3) Magic wand tool is super useful if you just finished your lineart and then, instead of having to draw out all the colours, you just select the inside portion of your lineart and fill in the selected area 

Hope these help ~