>>I am producing a magazine and sending it to a Printer first ever issue<<
I remember how scary this was!
Assuming you have LINKED rather than embedded graphic files (which is the recommended workflow) make sure that what you send to the printer contains:
* all graphics files (at 100% of the size used in the publication) - in other words, don't do the final resizing in PM, do it in Photoshop after establishing the correct size in your PM layout
* all fonts - and if you have used Type 1 fonts, send both the .PFM and .PFB components. Also remember if you have used italics/bold/bold italics, that these are SEPARATE fonts, and to send these as well. Also any symbol fonts you may have used.
* check that if NOT in full process colour e.g. spots or just greyscale, that no elements use the wrong sort of colour, which will generate extra film and plates (expensive).
Have you checked with the printer about imposition? I assume you have set up the pages in 'readers spreads'? Let the printer do the imposition for you as you don't always know what size sheet he will be printing your publication on.
Finally, here's a list I found over on the prepress newsgroup (with a few extra comments by me for clarification):
Set up documents to reflect finished trimmed page size
Extend objects outside the trim area for bleed where appropriate
Always submit all and only fonts used in the document - not every font on the system
Work in the correct colour space for the final product i.e. CMYK/spot NOT RGB
Use (raster) graphics of an adequate but not excessive resolution (300 dpi is usually the best)
Use vector based graphics for logos etc
Check panel widths for folded brochures by making a mockup and measuring it.
Always knock out white text
Always overprint foils and die cuts
Don't impose anything unless you are explicitly asked to do so
Make clipping paths in Photoshop and save as eps
Avoid leaving Alpha channels, transfer functions or halftone information in Photoshop files.
Don't use JPGs
Check that your printer can process DCS files before using them, and tell them that they have been used.
Read your final copy BEFORE submitting it for printing
And most importantly of all - COMMUNICATE with the printer.
