Showing up late
Wherever you go and no matter how big or small a company is, it’s important to recognize the value of time. And when you’re starting a new job, coming in to work on time is imperative. Avoid showing up late not only on the first day but in the rest of your stay in the company. Being tardy creates a negative impression. Create a good one and build a good reputation by being prompt to work.

Turning down opportunities to learn something new
Whether or not your new role is somewhat similar to your previous job, there will always be something new to learn. Perhaps it’s an entirely new knowledge or just a new way of getting your things done. The important thing is you take every opportunity to learn something that will help you perform your job better. Be open to learning new techniques and try applying them on your new role. You might be surprised at how much efficient it can make you.

Dressing up inappropriately
Companies usually set rules on which clothing are acceptable for the office. Take time to learn about what constitutes the dress code and be sure to adhere to it. The last thing you want is to get everybody’s, especially the managers' attention because you don’t look professional or you’re dressing up inappropriately. It won’t hurt to observe your new company’s rules and set the right impression.

Complaining about former company or boss
It’s completely normal to hate something about your previous company - whether it’s your role, your boss, the culture. But whatever it is that annoyed you in your previous job, it’s always better if you keep it to yourself instead of complaining about it. Speaking ill of the past job experiences you had, whether they hold true or not, isn’t a great way to start off in your new job. Start on a clean slate, start fresh and new, build a good career and relationships with your colleagues by embracing more positivity.

Sharing too much personal information
You might not find anything wrong with sharing some personal stuff with your coworkers but remember that timing is everything. If you’ve just started working with them, it might not be an ideal decision to share too much information just yet. Start building good working relationships first and a deeper friendship may just eventually follow. Just be careful with who you’re sharing information with.