Sta.sh
hopeful this can be useful for you guys
lets see - i learn all of this thing at SAI tutorial and YOUTUBE - also a good sensei
youtube have a lot of tutorial that i think it can help you for improving -
BEWARE !! XDDD
this will be a long ONE !!!
i give you all the link that i learn SAI coloring -
on YOUTUBE :
1. here is the SAI coloring at Youtube ( this is teach you how to coloring using markers - its my base coloring )
>>> [link]
2. this one is another YOUTUBE coloring with SAI - using Cellshade style :
>>> [link]
3. this one teach you how to blending
>>> [link]
4. CELLSHADE painting
>>> [link]
5. another cellshade painting
>>> [link]
6. MASTER of 1 LAYERS hahaha 8'D
>>> [link]
7. i learn how to coloring hair with this video
>>> [link]
8. speed painting art chibi cute + help you learn base coloring
>>> [link]
9. master of painting
>>> [link]
10. cellshade CG
>>> [link]
ps * learn all of it from youtube is really useful - you can start to try it- like how they coloring their hair and skin and shadowing
also - you must always check the layers there - its really important to knowing how they keep all the layers in the right direction 
i recommended you too check others video - since all of it will useful
SAI tutorial at DA :
for this one - i dont really have any good one - i just have about 3 that i download and use it until now -
since my english is not really good - so far i just really use this 3 - and i dont really understand the others as well - but i recommended this all 3 - because i think its already have all the tools and explanation is really good
1. SAI tutorial coloring and tips
>>> [link]
PS ^ just go there - and you will be find the other 3 links at the art
HOPE IT HELPS MY DEAR !
sorry if i cant help so much ;__; my english is really bad - so i dont have any good recommendation for SAI at DA-
i only learn all of it from YOUTUBE - and sometimes - i google for searching a good tips.
like this one :
>>> [link]
and this one ( with full of other tutorial link - just click whatever you want to learn )
>>> [link]
this is also a USEFULL COLLECTION SAI TUTORIAL >>> [link]
PS : if you still confused with all of it - i suggest you go to here >>> [link]
Its a youtube video - explaining all the basic tools and else - i learn this when i use SAI for the first time.
and last one - if you guys want to know what tools im using for my coloring >>> [link]
ENJOY <3 
I'm so sorry for you because of work, no holidays, etc. ;___; Stay strong! >3<
thank you so much
hahaha im happy i can help you guys
And if you're interested, I submited your birthday present on dA (picture with chibi! England and Amercia with big cupcake and mochi) :''3