The color proof will give a good (though never perfect) indication of what the final print will look like. It needs to be checked for registration, clarity, density of color and accuracy of color. Registration is quite easily checked with the aid of the registration marks on the proof, but other aspects of proof checking need some skill. Unless you have a lot of experience with process color printing, it's best to interpret the color proof on the basis of your printers' knowledge.

If things need correction-and, bearing in mind the relative costs of film separations and the print job itself, it's not unusual to remake separations- talk to both your imagesetting bureau and your printers about how best to make the changes.
When you're satisfied with the color proof, the printers can make printing plates from the separations and print your job on the press.