Choosing papers that will compliment your colours and style is important. Especially if you are considering D.I.Y Buy samples of several colours and check that they will print as you would like through your printer.
Try several fonts, to make certain these also compliment the theme.
A shimmer or metallic paper is one that will throw different colours when moved around in the light. Generally chosen for your invitations as they are light, attractive and will layer well without bulk when you are considering using several colours.
Sometimes the shimmer papers do not photograph well, and need to be seen to appreciate the beauty of their colours.