A couple of tips from someone who's got the T shirt:
I can't think of a single friend flying Part 121 who got a violation. I have several friends that got violations flying 135. Protect your certificate. 135 is the soft underbelly of professional aviation. Many cut corners. I flew for one great one (Ameriflight) and two really poor choices. The two commuters I worked for were 135, but today, they are all 121. The business is low margin and cut throat. It's common for one operation to rat out its competitor.
The FAA inspectors don't care and will turn on you on a dime. Generally, it's easier to violate a pilot than to take enforcement action against the company. Often, violating the pilots is used to get them to turn on the company.
The best protection comes from one thing. Know the regulations and your operation specifications cold. Don't expect your company to spoon feed you or to point out where they may be cutting a corner. Know the corners of both of those too. Often, I found it easier to explain to my bosses how we could operate legally instead of explaining why I couldn't go.
Grow a set, or at least find yours. Bad companies will paint you into a corner. Sometimes you just have to say no. Be firm and be ready to walk. It's tough to sit in the CP office and see a stack of resumes and tell them no. That means that you have to keep your professional contacts up to date and your finances in check.
Treat all of your follow employees with respect and curtesy. You never know where your next job is coming from. It's a small world and reputations can be made or lost. It's common to be someone's captain today and tomorrow, he's your co-pilot. This goes for other, non pilot employees. You never know who's who and sometimes it's a comment from a non pilot employee that can make the difference.
Leave with dignity. First, everyone in the business knows that good and bad operators out there. No need to explain. Think about what you're posting on social media too. Give notice and don't burn bridges, no matter how bad the company. Be a class act. That will follow you.
Last thing: Have fun! Some of the best flying and the best flying stories came from my days in the trenches. Military pilots will never understand what you have been through.