If you are asking about printing them yourself, say, on an ink jet printer, I heartily recommend Avery product no. 8871 -- 10 up, nice weight, bright white, ink jet matte coated, no cutting, no perfs (they peel off clean after printing). Keep your file in RGB mode so that you can color manage the output.
If you are asking about having them printed commercially, I strongly recommend you talk to your printer. You will most likely be asked to provide a CMYK file.
=-= Harron =-=