No matter what the need, few security organizations are as dedicated to helping us InfoSec Pros as SANS.
Pentesting. Let's call it what it is: Painstaking. You spend hours gathering information on a possible issue. You spend more hours outlining a test. Even more hours are spent pitching the test as worthy. You execute said testing, all the while observing proper research methodology and doing all you can to avoids tainting the results. And when all that's done? It's now your task to rephrase your high-tech findings into actionable intel your organization can appreciate, understand, and use.
SANS trainings help with all this, of course. And their white papers and blogs can open your mindset to new opportunities. But best of all those resources are the wonderful posters SANS has produced since their early days. The Spring 2015 Pentesting poster is available! This is why you want a copy.