How do you Paint Tool SAI?

I’m new to this program and it’s almost overwhelming. Plus, I’m not good at shading and blending colors. I tried using a blur tool but it makes the color blending look strange.
 

Contrary to what many people think, you do not need to blend or blur to be able to shade. An artist who knows how shading works can shade effectively wth limited palettes and no blending. You mostly need to know where shadows fall; shadows are created where a light source does not hit.
 
I have yet to try digital painting (soon though), but I hear what you do to blend is not using blur or smudge tools but by using opacity settings and pen pressure.

@Pix3M  
I can confirm that using pressure-controlled opacity/flow and on-screen paint mixing is the way to blend 99% of the time. Smudge tool is absolutely horrible at blending, but it can make magic in certain places.

@Pix3M  
then all depends of the light you want to put, if it’s on the full sun and want something very contrasted, blending of course is a no, but having some darker or softer pic, with low contrast, i dunno but i can’t help but blend it like amofo.
 
 
@Grieffon  
well, there’s still photoshop for that. even an old version will blend perfectly.