This is  specifically for all engineering graduates,  I believe this applies for the many young hopefuls walking into their first company.
Falling more in love with the company than the job
Probably one of the biggest mistakes they do. They truly believed that if they got into the company they wanted, they would eventually find the role that was right for them. What was more painful was that they gave up an amazing role in a different company because they liked the branding of my-then-employer.
Treating work projects like school assignments
 It’s natural that you’ll want to treat your projects at work like your assignments at school. After all, you just spent over 16 years being a good student, but you’ll need to shift your mindset. Work projects take much longer to complete, the end requirements are sometimes ambiguous, and you need to collaborate with other people more than you did in school. Take your time to do the project well.
Not asking for help
 In school, it was pretty obvious when you needed help and how to get help. You got a bad grade on an assignment so you went to office hours. (Or you just got a bad grade on an assignment and didn’t go to office hours…no judgment :P) You’ll struggle from time to time at work, and that’s natural. Learn how to ask your manager for help. And don’t only ask for help with technical skills. Also ask for help in how to become a better employee over all.
Ignoring interpersonal skills
I think this one gets ignored by a lot of new graduates, especially technical people like engineers. Technical skills are the price of entry. You will get better over time and you will get your first few promotions based on technical skills. But the technical skills will only get you so far. If you want to get more promotions in your career, you need to focus on interpersonal skills as well: leadership skills, managing down, managing up, and understanding business strategy for your industry.
Believing that your first job is highly deterministic for the rest of your career.
I remember being an undergrad and being surrounded by people absolutely pining over particular choice jobs. Picking a job or employer is important, no doubt. And certain jobs can lead to relationships that DO determine the rest of your career. But to assume that your first job will inexorably lead to one particular brand of career or lifestyle, or that changing your mind or making a mistake in job selection is catastrophic, is the wrong attitude IMO.
Lacks collaborator skills
It takes a great entrepreneur with vision to start a business, but it requires strong leadership collaboration skills and a collaboration of many people to make it a success.
Collaboration is working together to achieve a goal. It is a recursive process where two or more people or organizations work together to realize shared goals. Note that collaboration is NOT cooperation … it is more than the intersection of common goals, but a collective determination to reach an identical objective by sharing knowledge, learning, and building consensus.
Not a good listener
Some people are very good at speaking, telling their stories and being able to inspire others. But being a good listener is often more important than speaking. It gives a deeper level of understanding about someone’s situation, and helps to know what words are best to use and what words should be avoided
Value quality over quantityÂ
If you can, try to work as quickly as possible, but do not sacrifice the quality of your work for the sake of more output. Your manager and colleagues will remember negatively the time you broke the software build with a code check-in, even if it was delivered a week ahead of time.
Fail to step up early and dive in on something important.
Time to reach out and get that experience. Jump in. Communicate eagerness to get involved in something meaningful and important. Consider extra work if necessary. Every boss likes to hear: I’ll take care of that! It may be menial, but if it’s important it matters.
Improper resume profile build-up
A resume should be build in a proper way, which can  make an impact on the recruiter directly, the presentation should be cut to clear that what they are into, what they can expect in their company profile.
Neglecting internship and mentorship
If you are an engineering student or a professional degree holder then it is necessary to do few internship and mentorship which will directly add on a strong point in your resume that you have also gain not only theoretical knowledge, but also some practical experience which is must for the corporate world right now.
