Being professional while young is a challenge but it is doable if you keep in mind some basic principles.
1) Everyone knows you are young. Just do not remind them of it constantly. How to do this is by avoiding using your cell phone if you can. The stereotype is that people younger than 25 are always on their phone when in reality we are all on our phones ALL the time. It is not fair to be unfairly judged by this but it is a reality that you need to think of at all times when on the job and presenting yourself professionally.
2) Dress appropriately for the office – not the beach. Be as well put together on a budget as possible – learn more on my Dress for Success post.
3) Be on time – always. Being early during the internship is acceptable so long as you can keep yourself busy. Do not be late.
4) Keep yourself busy – find stuff to do. Do not be a nuisance by asking “what do you need me to do” every few minutes. It is ok and acceptable to look for guidance and help when needed but it is best to be as self motivated and driven as possible. It is better to get a quick check in during the morning and then find new work to do and focus on throughout the day.
5) Learn as much as you can – do stretch assignments and be open to learning as much as you can while there.
6) Build your network while there – keep an eye out on creating lasting connections and find ways to help those around you in any way – however small.
Good luck on the internship and do what you can to build out your resume as much as possible! Happy hunting!
Lisa Vento Nielsen