This is a list of resources that we have found very helpful in working with sewing patterns. The links lead to listings on Amazon.com, where you can find more information about each book and purchase those that will be helpful to you.
The Complete Photo Guide to Perfect Fitting by Sarah Veblen is an in-depth guide to making fitting adjustments using a muslin.
Create the Perfect Fit, Measuring and Pattern Fitting for Real Sewing Solutions by Joi Mahon provides extensive detail on comparing body measurements to sewing patterns to execute substantial adjustments to the pattern before constructing your first muslin.
Fit for Real People by Pati Palmer and Marta Alto focuses on fitting with the tissue pattern. It also includes an abundance of illustrations showing how to make flat pattern adjustments to solve fit problems.
Pants for Real People by Pati Palmer and Marta Alto follows the same format as their book Fit for Real People, but it exclusively addresses fitting pants.