GUEST COMMENT: A full list of the fatal errors investment banking interns make

At the end of a failed summer internship, interns often ask me how and why it all went wrong: why didn't they get the offer?

Sometimes it's down to fit and general aptitude - things that can't be changed. Often, however, it's because good interns make silly mistakes which ruin their chances. These are avoidable. You don't need to do them, so don't.

They include:

1) Bad attitude

Internships are hard, but you need to maintain professionalism. An all-nighter or being drained is no excuse to come in late or look like hell the next day.

You need to manage your time, your networking, your work and your energy levels properly.

Self-management and a good attitude are qualities we look for.

Some summer analysts want it so bad that they absolutely kill themselves; their attention to detail and professionalism suffer.

Many of the jobs given to interns are dull and you may feel you're above it. You're not.

2) Being late

Bankers are notorious for running late. We get caught on the phone, caught amidst a difficult trade or in a long meeting. You, as an intern, do not have this luxury.

Manoeuvring your way around a trading floor isn't easy.

PLAN AHEAD. Make sure the night before you know the exact desk location of your rotation person, know who you are meeting, what he does and make sure you are waiting at the end of his/her row 5mins early.

In the mornings, arrive before everyone else on the desk you are interested in. Be there to say good morning and observe quietly. Mornings are a hive of activity; you can learn a lot.

3) Gossiping

There is nothing worse than MD's, ED's etc seeing you scuttle off with one of your buds for a quick gossip and chit chat.

Meet for a beer after work, meet outside the building and walk to grab lunch but don't be seen loitering around people's desks and 'gossiping' when you could be number-crunching at the desk.

4) Inappropriate clothing

As the summer carries on and it gets warmer, you get more comfortable and we often see interns slipping into their university ways.

We do have air conditioning so the weather is not an excuse.

It is important to be comfortable while looking as though an MD could take you to any client meeting at any time and know you would look smart and presentable. Ladies, sky high heels, short skirts, vest tops (EVEN UNDER A JACKET) are a no! Avoid bangles and things that jingle.

Gents, always have a tie in your bag and wear your jacket in EVERY day.

5) Dullness

Small things make a difference. If you are invited out for a beer after work, go. And then go back to the office to finish up when you're done. Be a fun person to be around - just try to fit in and conform to the norms of your office/group. Make some friends!

6) Causing irritation

Don't ask too many questions. Some questions are good: they allow you to learn; they show interest.

However, year after year interns fall into the same trap. They are given a project and they pretend they understand it and they know what to do. But they don't. 20 times a day, every day, they then return with various questions.

Don't do this.

The best thing you can do is make sure you understand the project at the point it is given to you. Go off and think about it in depth. Collect up a list of questions and then go back to the person to ask them. After this point you should not need to go back until the project is finished.

7) Isolation from peers

How you interact with the other interns in your class is closely monitored by all. While I understand you are all in competition for full-time placements, backstabbing and a lack of team mentality is frowned on. It is important you are seen to be well-liked and popular in your class.

To each other you are a vital source of information and can help each other with contacts.

We sit next to the people we work with 15hrs a day 5days a week, we travel together and attend evening client events together. I spend more time with my colleagues than I do my family. We need to get on. Interns who help each other out, put their peers forward for roles etc will do well.

8) A lack of humility

One of the most desired qualities for many people in a friend, mate or work colleague is humility. Don't act like you know everything. People assume this is your first internship and we don't expect you to have all the answers nor act like you do. Be humble, be willing to learn and you will do well.

9) Dismissing HR

Far too many interns dismiss HR as administrative people who have no power. YOU ARE WRONG. Do not dismiss them - they are very powerful. Make sure you have good 2-way conversational flow with HR. I'm not suggesting you speak with yours daily, but do try to touch base once every two weeks. Tell them which direction you feel you are going in and which desks you are doing projects for. They have the inside information to guide you to where to focus yourself. They will also tell you where to give up.

The author is a junior banker who has worked at several top firms.