A few questions about CYMK separations in Adobe photoshop CS

[Mark @ Hurricane Printing]

Do you  tweak an image BEFORE you begin the Real process separations or can you tweak AFTER the steps? Say I wanted to bump down the black in an image….or maybe bump up the red in an image..and I do this thru curves…do I do this before I begin seps or can I do it afterwards. Because afterwards I see how a pic needs to be tweaked some…I just need to know when I should do this.

I use these steps for CYMK seps:

Process Separations

Are the "color settings" universal for any way to do CYMK seps?

What should my "color settings" (edit/color settings) be set at? Currently they are set at the following:

Settings: Custom

Working Spaces:
RGB: Apple RGB
CMYK: U.S. Web Coated (SWOP) v2
Gray: Dot Gain: 20%
Spot: Dot Gain: 30%

Color Management Policies:
RGB: Preserve Embedded Profiles
CMYK: Off
Gray: Off

are these settings acceptable for the above tutorial? or do I have to do something different in color settings? Or are the settings above universal for any type of CYMK separation process?

The frequency for all 4 colors is at 70
and the angle starts at 45 for black...75 for cyan...105 for magenta...135 for yellow. (all of this info is from the tutorial above)

Thanks for any insight you can give.

[Sbrem]

since the instructions call for converting to bitmap/halftones in the middle of the process, I would recommend you do your tweaking before starting the process. I also recommend tweaking the file beforehand as a general practice as well.

Steve

[Lizard]

First thing is you need to download ink color profiles from your ink manufacturer.  If they do not have you need a different brand of ink.  For example switch colors settings to different color profiles and you will see how the image changes.  If the color profile does not match your inks you have no clue what you are going to get.  If someone is doing seps for you and the do not know what inks you are going to use you have no clue what you are going to get.