When selecting the correct color for your car you have a choice of factory colors or a custum color.
Factory color chip charts can be found at your local automotive supply center. You may also find color charts online but they will be difficult to understand the final color.

Whether you are selecting a specialty color or matching your exact factory paint it is always best to stay within the manufacturers paint line.
You can select paint colors from your year or from surrounding years or historic colors. Although you may find a color from a different manufacturer that seems pleasing a lot of time and money has gone into the choosing of colors for specific models of vehicles.

For instance if you were to paint a Ford Mustang the same color as a Chevy Camaro the color may look good or it may look odd.

If you are selecting paint based on factory colors you will always have a broad range of colors that match the style of the designers of that manufacturers vehicles.

When selecting metallic colors is important to view the color in natural light. If possible you should take the color chart look outside and view the metallic color in daylight or at least take the color chart book to a window.

It is also possible to mix a color of paint from a chip color that you supply. Your paint supplier in scan the color into the system and give you a preview of the resulting color and then mix a small sample that you can test.

Custom colors should that cost dramatically more than factory colors unless you are picking factory colors that are supplied from a limited color line.

So for best results you want to select a color that is based on your exact vehicle type, other vehicles of the same year and manufacturer, adjacent years, or historic years from the same manufacturer.

For custom colors you may want to try the color on the vehicle by using Photoshop or painting a small model of the vehicle if available from Hobby Shop.

You should never expect that the color in your mind will result from a chip that you pick from a book if there are no other examples that you can judge from. Quick internet searches of a vehicle that you want to paint may provide similar colors to the one you are picking.

Basic colors such as white, black, silver or other base colors can be selected without problem but remember every manufacturer has their own paint system. A Chevrolet silver will not be the same as a Porsche silver.

Final Note
Picking a color is something that you will have to live with for many years. It may also add or subtract from the value of your vehicle. Dramatic color changes from manufacturer colors should be avoided unless you understand that your choice may result in a loss of value or personal satisfaction.