Designing a CD booklet and covers

[Mitch Essence]

Hey guys, My name is Mitch Essence.
I am a guitarist currently working on the design
of the booklet of my new album. Also covers for
CD jewel case.

My question is this:

Should the images and art shapes for these pages (Covers, booklet)
be designed in their original dimensions and then resized in 12X12cm
(CD size) or should designing begin on a 12X12cm 'digital canvas' and
everything resized to fit that template?

Also in a transparent jewel case CD its narrow left side includes band
name and album title, so should designing consist of a one piece canvas
for Front cover, narrow left side and back cover for later printing?

Thanks you!

 

[Stationery Direct]

I would speak to whoever is printing these and just ask them what they require exactly, they will most likely have a template you can use.