Ensure you convert all RGB colours to CMYK. This is vital for your job to produce desirable results.
Please allow for a difference in colour between what is shown on your screen and what is printed. When printing in CMYK (Cyan, Magenta, Yellow, Black), various factors will affect the colour. You cannot determine how the colour will print by what you see on your screen, every screen is different and every printer prints each colour differently. Perfect consistency is not guaranteed, this is simply the nature of printing in CMYK. There is potentially a 5% variance in colour from the first proof to the final product. Never underestimate the difference a stock can make to your colours. When choosing a colour please take into account what stock it will be printed on. A colour will appear differently when printed on different stocks.