Symbol Spinner

Click or drag over the symbol instances you want to stain with the colorization color. The amount of colorization gradually increases, and the symbol instance’s color gradually changes to the colorization color.

Hold down Alt (Windows) or Option (Mac OS) as you click or drag to decrease the colorization amount and reveal more of the original symbol color.

Hold down Shift as you click or drag to keep the colorization amount constant, while gradually changing the color of the symbol instances to the colorization color.

Print Document Profiles

General

Set the page size and orientation, specify how many pages to print, scale the artwork, specify tiling options and choose which layers to print.
Marks & Bleed

Select printer’s marks and create a bleed.
Output

Create color separations.
Graphics

Set printing options for paths, fonts, PostScript files, gradients, meshes, and blends.
Color Management

Select a color profile and rendering intent for printing.
Advanced

Control the flattening (or possible rasterization) of vector artwork during printing.
Summary

View and save a summary of print settings.

A high line-screen ruling uses small dots; a low screen ruling uses large dots. The most important factor in choosing a line-screen ruling is the type of printing press your job uses. Ask your print shop how fine a line screen its press can hold, and make your choices accordingly.


SOURCE:
https://helpx.adobe.com/illustrator/using/setting-documents-printing.html

9-slice scaling

https://creativepro.com/understanding-illustrator-s-9-slice-scaling/

essential for web graphics
9-slice scaling is useful only when applied to symbols that will be viewed with the Flash Player (as SWF).
Since it’s an effect applied in the Flash Player, you won’t be able to preview the result of a 9-slice scale unless you’re viewing your art in the Flash Player.


1. f8 - define a symbol
2. Enable Guides for 9-slice scaling. The symbol must be defined as a Movie Clip (Figure 1).

 you can preview the proper 9-slice scale result by checking Enable Live Preview from the Control menu.




4 guides create 9 different regions on the screen

middle - both horizontally and vertically

upper left, upper right, lower left, lower right are all areas that do not scale at all.

SOURCE:
https://creativepro.com/understanding-illustrator-s-9-slice-scaling/

Save Selection Feature - Saves Time

Save Selection put the skill on a different level because marquee-selecting in illustrator, and then, shift+clicking object to combine the selection as a whole can take up loads of time. This save selection feature saves the day for your new professional workflow. This is something that I was looking for in Illustrator for a long time but couldn't find it. This will make it easier to prioritize certain tasks when working on freelance projects.