Preparing images for printing

[nickd01]

What is the are the best methods of extracting as much quality as possible out of a print?

For example, if I want an A3 (approx) print out of my 5D then what can I do in Photoshop / Lightroom to help me get the best possible quality and colours?

There are so many sharpening masks, JPEG export options etc I'm unsure where to start!

Thanks