I've been doing color printing for close to a year now. I'm far from an expert, but I've found that the most valuable tool for me is a shot of a gray card. It's relatively easy to get good color balance on a gray card because it's gray and because I can compre it directly to the print. If other subjects on the same roll are shot in similar light, their color balance and exposure won't vary by much, so even if they're horrifically difficult to balance (like autumn leaves -- I had a terrible time with such a shot a few days ago!), the task becomes much easier by using the gray card frame to get the color balance.
In theory, if you consistently use the same film, film developer, paper, paper developer, and developing conditions (particularly temperature), color balance shouldn't change much from one roll to another. I've got quite a wide variety of films, though, so my filtration's all over the map. (I'm starting to narrow my film selection to help simplify printing, but there's all the stuff I've already shot.)