Artwork supply recommendations

Vector. If you have your logo in Vector EPS format, then always use it. Vector EPS files are scalable, unlike JPEGs and other image types, which suffer in quality the larger they are used.

Find out your Pantone colours. Most Vector EPS logos will have been designed using Pantone Matching System colours, when you send your logo, let the supplier know all the pantone colours in your logo.

Try and use ZIP to send files (commonly "winzip", but other compression software such as "Stuffit" can ZIP a file too). ZIPPING your logo or image before you send it over email or FTP not only reduces the file size a little (or a lot) it also protects your file from corruption, this is especially useful for EPS files.

Quality. If you're sending a photographic image as artwork, for example a TIFF or a JPEG, use the best quality version available. Its best to ask for some guidelines by the supplier as requirements are different for each print method.

Try and use FTP instead of email for transferring files. There are many ways to use FTP, one of the easiest is to visit yousendit.com and try it out, (other FTP websites are available). There are many benefits to using FTP over email, but the main one is that it keeps everyones' emails small and the archiving easier to manage.

Send brand guidelines if you have them. Lots of companies have a PDF file or a web page detailing brand guidelines, send this reference to your supplier so that they can help you stay "on brand"

Line thicknesses. On some small jobs like pens and pin badges, there may be a minimum thickness of line that can be printed, if your logo has some particularly thin lines in it and is being reduced down in size, always check with your supplier if they will print correctly, it may be that you can ask the supplier to thicken them up a little.

Overprints. Some artwork, (particularly spot colour logos) is made up of areas of colour that may need to overprint in order to achieve the correct appearance. (Such as an area of black overprinting a colour behind to achieve a shadow effect). Its important that this overprinting is mentioned to your supplier upfront, as some print methods may not be able to reproduce this effect.

White. Always check with your supplier on how to supply artwork if you're printing onto a coloured item.
Often, when printing onto coloured items such as tshirts, a white layer is printed first, this ensures that any subsequent colour isn't tainted by the material colour. Even a white logo will benefit from being printed twice, once as a base colour, then secondly as the top colour.