Many jobs are printed either partly or wholly from line blocks, which are usually produced by photo-etching in polymer or metal. I can arrange for the blocks to be made and in this case I can accept original artwork (via email) in PDF format.
Multi-colour work often requires ‘trapping’ to ensure that there are no unprinted gaps between colours that are intended to butt together. It is worth spending time getting this right – the results will almost always justify the effort. Other considerations might include providing suitable bleed on the artwork and allowing space for gripping and trimming the sheet.
If you are intending to supply artwork for block-making, talk to me before you get your client to sign off the design.