I'm preparing images for a large print (90x 60 cm, roughly 35 x 24 inch) for my first customer. Since this is the first time I do this, I was hoping for some advice.
What I've found so far browsing through older posts and other web resources is that I should up res the images to the correct size, using some form of interpolation. Also I need to sharpen the image after resizing, but I'm a bit inconclusive about what settings to use.
Which interpolation technique do you use for such large prints?
Which sharpening settings? My Photoshop book tells me that I need to use a 3 px radius setting for a 300 dpi print, but I see other settings mentioned here on BPN.
If I understand correctly, I need to slightly oversharpen the image for print, because of the bleeding of the ink on the paper. However, I'll be using direct printing on Forex foam plate, for which I'm unsure whether there will be any bleeding.
Color management is set, I have an ICC profile for this process from the printer.

Of course I want the images to look stunning, so any help and advice are greatly appreciated (also beyond the answers to the above questions)!