Learning how to effectively work with a variety of employees and managers is a lifelong journey...take the time to listen and consciously observe others paying close attention to preferred communication styles, personality types, etc.
I believe the greatest challenge following that would be in understanding the unique needs of your customer and how you can effectively meet their needs. I would say flexibility is the key and always keep an open mind for learning.
Work life balance is important, so definitely be true to yourself in terms of your needs when making an employment decision.
Will there be busy times, yes of course, you may pull overtime several times of the year...
Vacation days exist for a reason so utilize them when you feel you need a bit of a break from the routine of it all.
Most highly successful companies realize that the most productive workers are those who have this balance. Their high productivity stems from their loyalty and dedication to the company, which is built through an environment that values and strong work/life balance.
Being new in your career, you probably want to demonstrate your work ethic and are eager to move up internally, but not at the expense of your mental/physical health
For most of us, job satisfaction comes from the challenge to accomplish something that we are uniquely qualified to tackle.