What advice would you give someone who is about to start a new job?

Observe and ask questions. Find out who the most important people are in terms of helping you to get things done and be successful in your role. Take notes. If a review is not offered as you go through new things, ask if you can do that to ensure you completely understand what is expected of you. Be open and energetic! A great attitude goes a long way toward others wanting to help you succeed.

Agree with above and ...

I also suggest structuring your first 90 days with a list of target contacts, questions, and a plan for capturing low-hanging opportunities to deliver results, then ranking the more difficult challenges / objectives for subsequent plans going forward.

The first three months is critical, and while on-boarding arguably takes 12 months depending on level and organization, many will form their opinions early. Even if you are having "the same on-boarding problems" that everyone else is having, it is better to avoid that as the narrative when colleagues are talking about you or your performance.

Our job seeker guru @snagajob Amy White offers these words of wisdom:

Take a deep breath.

Find a mentor to show you the ropes.

Keep in mind that no matter what your job, it's critical to the company - and approach it with the diligence that responsibility warrants.

Understand your purpose so you know exactly where you fit. Do not just find a job but find a career, something that leads you to what you have been created to be. Picking anything can be dangerous if there is no plan to transition from there to where you are really meant to be. Discover you then you will discover where you fit. God bless.

Let's face it - the first week on any new job is horrible. A new employee can get past the uncertainty and the unknowns by spending the first week talking, listening and learning the culture. Making one friend at a time has always helped me get past the first week. Once I feel more comfortable and accepted as part of the team, I can relax and start to show my true self and become productive.

Listen, ask questions, and clarify. Learn the organization. Understand what has brought the operation to where it is today (what key opportunities and challenges exist, what have been the key wins, etc.), and what the desired future looks like.

Also, don't underestimate the value of building strong working relationships early on. Don't wait for the bridges to build themselves. Be appropriately available, understand the culture, and recognize the value of existing informal networks.

From a booklet I wrote a couple of years back. Here are the main ideas without a lot of explaination.

20 Things You Need to Know for Job Success

You Got the Job, Now Do It Well!
How to Succeed at Your Job in 20 Steps

Congratulations, You're Hired! What Do You Do Now?
Essentials Everyone Needs to Win at Work

1—You Chose to be Here So Choose to do Your Best
2—Plan For Success Not Mediocrity:

3—Think Career, Not Paycheck.
4—Recognize that Every Job is Important:
5—Take Responsibility: "It's not my job. It's not my fault. I couldn't help it is not aceptable
6—Change:. Go beyond your comfort zone.
7— Never Quit Learning:
8—Build On Your Strengths:
9—Take Initiative:
10—Identify What's Most Important To Your Boss and Others: Figure out what things are most important to your boss and others and make sure you do them well
11—Dress Better than You Need to Dress:
12—Don't Bring Home to Work:
13—Handle Conflicts with Co-Workers Diplomatically
14—Do What's Right:.
15—Be Your Authentic Self
16—Develop a Positive Self-Image: It's not who you are, but who you think you are.
17–Being Polite Means Making Others Comfortable:
18—Just Do It:
19—Actions Count, Intentions Don't
20—Be the Best You Can Be: