Whether you conduct a self-guided wine region tour or partake in a guided tour offered by a local tour guide company depends on your personal preference. A tour company they will offer travel to a predetermined list of wineries by one of a various means of transportation, limo, bus or even bicycle.
If you elect the self-guided option, be sure to get a good map before striking out on your adventure.
The advantage of the second option is that, if you are not familiar with the area and/or the wineries themselves, this method can be easy and non-stressful. However, if you are familiar or prefer a more individualized experience with less likelihood of a crowd, then the first option is probably better for you.
A number of the larger wineries offer tours of their facility where a staff member will guide you through the winery and explain the process of making the various types of wine they produce. It is beneficial to go on a tour as it will provide information that will help with your understanding of different varietals and wine making processes. This information may be beneficial when making wine selections.
I suggest taking a tour at one of the larger facilities as they will most likely make both reds and whites, as well as use more than one fermentation process.
At the conclusion of the tour I also suggest partaking in a wine tasting if offered. During the tasting the staff will review each wine and you will be able to relate back to the process used to create that wine. This will help give a better understanding of how the various flavours are created. Ultimately this may serve useful when you are staring at the shelves at your local wine merchant trying to decide which wine to purchase.