Many young professionals don’t realize that before stepping into the office on their first day of employment, their bosses and colleagues already know a lot about them. As soon as the company announces the new hire, employees will scope their new colleague via LinkedIn, Facebook, Twitter, and Instagram, and they’ll not only view their past work experience, but also see what they did last weekend.

With so much information available at our fingertips, it’s incredibly important to make sure you create a positive personal brand and channel that brand through your in-person and online presence. On your first day, you’re going to meet a variety of people, possibly including some senior executives, so you must be ready to have conversations with them.

When young professionals ask me for ways to make a great first impression at work, I tell them to consider the following strategies to best express their brands:

Conduct a social cleanse

Before your first day, scrub your social media profiles. While you should have already completed this during the interview process, you need to remove old photos from Facebook and Instagram. You don’t want your new boss seeing your casual vacation photos. Keep in mind that as an employee, you’re representing the company on and off the clock. Be sure to also exhibit knowledge about your industry or company by sharing relevant articles on LinkedIn or Twitter. This also shows your colleagues that you’re already dialed into trends and news.

Wear appropriate attire

While many offices now have business casual attire, you need to keep in mind the “business” part of casual. To make a great first impression, women should consider wearing blouses or button-down shirts and black pants, and men should consider wearing button-down shirts and khakis—all with appropriate footwear. I’m still astonished to see so many young employees dress very casually on their first day of work. A good rule of thumb is that if you wear a piece of clothing to the gym or the club, don’t wear it to the office.

Convey friendliness and politeness

Your initial behavior in the office is very important. You need to look people in the eye and give them a firm handshake. Whether you’re meeting a colleague the same age as you or someone 20 years older, you have 30 seconds to create a positive impression. Remember to ask questions, which is a great way to learn more about the person you’re meeting and shows them that you can hold a conversation. First impressions can also extend to digital communications, so write your first emails and speak on your first video or conference calls in a formal tone.

Prepare your story

As a new employee, you need to have your two-minute elevator pitch ready. You must speak eloquently about the role and responsibilities you’re undertaking in the organization, as well as your professional and educational background. Also, intertwine snippets about what you find exciting about your current field or how you chose your career; these details will enliven your story and illustrate your passion. Continuously practice your story before heading into the office on the first day, so you know exactly what to say when you meet your new colleagues.

Making a great first impression can have a lasting impact on your career at an organization. It shows your excitement for your new role, your enthusiasm for the industry in which you work, and your desire to succeed at your new company. If you’re not prepared, you risk spending weeks trying to repair your image.