Did this for a friend, It may not be 100% accurate but I hope it helps someone somewhere.
1) Know what you desire of the end result. (This doesn't mean know the End Result itself, just to know any parameters you want first and foremost.)
2) Set up your Canvas. Usually 4000X3000 is my preference, as it allows you detail but not smotherlingly huge and laggy. Create in order Ink Folder, Color Folder, Sketch Folder, Ref Folder, Background Folder.
3) Collect all your references into your Ref Folder by bringing them into SAI, using the Ctrl+A to select them, then copy paste them into your main file. It helps to reduce the Ref Folders Opacity so that you can refocus your eyes at a glance instead of taking the time to turn the layer on and off while sketching.
4) Create a new Layer, name it something relevant. "<Character name>s Sketch" usually suffices.
5) Play around with your sketchwork. Figure out what works, what meets your desired end result's requirements. Don't get hyper focused on exact details. Rough broad strokes.
6) Once you have a 'form' of a sketch. Create a new layer named "BackgroundSketch" And place in your background folder.
7) Figure out where your points of no return are, if any, or whether you need a horizon for your image. *KEEP IT SIMPLE,* One to three lines, unless props are involved.
8) With your ground/horizon established, check your Sketch's skeleton. See if anything is odd, floating, or out of place. Start fleshing out your sketch more. Again, keep broad strokes. Start forming shapes body, muscles and basic frame. Don't be afraid to redraw a bone, or change an arm to a more appealing pose.
9) Keep in mind what the character is interacting with. Treat things like weapons, chairs or hand props as if they're part of the character, give them bones and flesh them out as well as you work. (TAKE AS MANY LAYERS AS YOU NEED FOR SKETCHING. BUT ALWAYS NAME)
10) Once your have your sketchwork completed, begin by making an inking layer in your inking folder.
11) Draw the rest of the fucking owl.
12) Don't be afraid to revise your sketch, or add more sketch to your sketch layer if you're having trouble with inking.
13) Longer strokes often give smoother results, try not to split smooth arcs (the curving of balls and breasts) into 2 brush strokes, instead try and get it in one.
14) Remember to add general ink detail first, worry about small detail for later (zippers, veins, fingers etc) there's no shame in leaving your character with mittens for hands in the early stages, just to get some kind of form down on the page.
15) Once you complete inking, It's time to create your "Base" Color. First and foremost, Make sure your Ink Folder is set to the "Selection Source". Create a new layer in your Color Folder and name it "<Chararacters Name> Color"
16) With you wand tool set to (Transparency, Strict) and with the target of (Selection Source), select outside of your character. Make sure to also catch things like open spaces under the arms, or any other openings that you don't want filled in.
18) If something is selected that you didn't expect/want. Either you have "Transp. Diff" set too high, or there is an opening in your ink, allowing the wand tool to grab inside your characters shape. Close any openings on an ink layer, then try again until success.
19) Invert selection, and CTRL+F (Which is the bucketfill shortcut) and fill with either your characters primary color, or white. Name this layer "<Character>Base Color"
20) Create a new layer atop this, and activate "Clipping Group". Now, it is bound to the base color layer, and even if you fill in colors outside the lines, it will not show past the borders of the lower layer.
21) Making sure your bucket is set to "Selection Source", Fill in colors as needed. Don't be afraid to get down and dirty with details, especially if you have flecks of white. You can also increase your Transp. Diff on your bucket fill if you're getting too many speckles without color. *Make sure to keep like-minded colors together. Dark Colors keep to dark, light colors keep to light. YOU WILL THANK YOURSELF LATER*
22) Make sure any new layers you create are also clipped to the "Base Color" Layer. Else they may slip passed the border of your inked lines.
23) Next to shading. Duplicate your Color folder, rename it Shading Folder. Using the Brightness and Contrast. to darken each duplicated layer without losing vibrancy. Light colors to approximately 50, Medium colors to about 40-30. Darkest colors need only 20-15.
24) Using your Erase tool, erase our portions of your base color to create light-sources. Keep in mind where your light source is as your work. And careful of erasing directly on edges unless your lightsource calls for it (Like if it's a lightsource directly behind your character.)
25) Blur where you erased on your base color layer. Use the edge or the center of the blur brush at your discretion. Change size as need but make sure not to catch the edges of your character in the circle of the brush, as it will pull from the outside.
26) Next to Shading and Luminosity. Create to layers directly above your "Shading" Folder. Name each Lumi and Shadow, and set each respectively to their name.
27) At your discretion, create shadows, creases and depth using your linebrush. *Keep in mind, drawing in a Shade Layer on Darker Colors MUST have a lighter Brush. The opposite applies to luminosity.*
28) You then blur your shadows to the desired effect. More often then not creases use center-blur techinques, while shadows in places like underboob, under-armpits use edge-blur techniques.
29) Remember your light-source? Well in your Lumi layer, add highlights as needed to the character, keeping in mind the direction of the light.
30) Blur as needed.
Good luck on Backgrounds! *passes out*
