You need a colorimeter (
Here is an example ) and possibly a better monitor.
Even once a good monitor is calibrated in, some colors may not show properly as monitors can not display all the colors that are capable of being printed or digitally captured, but it will get you close enough for the vast majority of prints and is infinitely better than using an uncalibrated monitor.
On the other end, you will want a good RIP software feeding your printer and a Pantone color chart so you know when your final print matches your input.