At age 12, you might have been able to get away with a lot of silly mistakes, but the world of business is cutthroat and highly competitive. Excuses and denial tend not to be valuable currencies, which is part of why only a fraction of the people who get started achieve true business success. Understanding this fact, it’s shocking that so many businesses fail to help themselves and make a parade of errors that you’d think even a prepubescent child would know how to avoid.

#1 – Stupid email addresses

How can you expect anybody in business to take you seriously if your email address pays homage to your college nickname, your weekend behaviors or simply the fact that you’re no one important? If you want to be taken seriously, scrap the somethinginappropriate@hotmail.com or nameandyearofbirth@gmail.com address and get a domain name for yourself and your business. The financial investment is pennies and the saved embarrassment is priceless.

#2 – Homemade signage

Even in some of the biggest global brands, I still stumble across insanely unprofessional homemade signs complete with someone’s finest “word art” or even messy handwriting. Whether it’s your opening hours, a simple “out of service” sign or a current promotion, be sure to do the job properly. Recently, I saw a business announce their recent win of a prestigious award by printing their winner’s certificate on a fading inkjet printer and taping it to the reception wall! Come on, everyone. This practice is not okay and has to stop immediately.

#3 – Trashy business cards

There really is no excuse in today’s world to have anything other than a stellar business card. The simple test is that if you ever have to apologize when passing it over, it clearly needs to change. Dog-eared corners and scribbled-out numbers are all too common — and let’s not forget the classic “I forgot my cards” line. New contacts can be made at any time, and not being ready to exchange cards is the business equivalent of forgetting your gym kit!

#4 – Pens, Pens, Pens

Imagine that you’ve spent years chasing a prospect, months in preparation, hours in negotiations and you finally get to the point of closing the deal. The customer has been convinced of your professionalism and dedication and now believes that you’re the right person for the job. Once you’re ready to seal the deal, you reach for a pen. The pen you hand your new customer commemorates your most recent hotel stay, announces your love of trade shows or, worse still, is encrusted with bite marks! If your business stationery doesn’t mean business, take today’s lunch break to make a shopping trip, or jump online now and grab yourself a writing instrument that’s fit for its intended purpose.

#5 – Personal Hygiene

Would you trust someone to offer you advice, take care of your business and deliver value on your investment if they couldn’t even take care of themselves? The way you present yourself supports and contributes to the success of all that you do, and whether you like it or not, the world judges you on how you look and how you smell. There is no room to cut corners here. Smelling like the men’s locker room, having morning-after breath or just failing to keep your fingernails in order could all shift you from a pass to an instant fail.

#6 – Timekeeping

Many people have access to at least five devices at any one time and somehow still fail to see the importance of arriving on time and staying punctual. Sure, maybe if you’ve invested in the latest Apple Watch, you may be able to blame the battery life, but let’s remember what happened when we were late for class. At my school, there was a zero tolerance policy for lateness and the same rules should apply in business. Whether meeting a client, a colleague or a supplier, arrive where you said you would at the time you said you would.

#7 – Note-Taking

Either 80 percent of the world has a perfect memory or a whole lot of people are downright lazy. I couldn’t possibly count the hours I’ve spent in meetings surrounded by people with no tools to take notes. What does it say to your boss, your client or your supplier if you can’t even show the courtesy of signaling that you believe something important may need to be discussed? What’s more, taking notes leads to more active listening. Increasing your presence in the room increases the respect you receive from others and the retention of the information you’ve discussed.

#8 – Social Media Transparency

You wouldn’t wear your employer’s uniform when downing flaming tequila shots at the bar or share your political or religious views directly when meeting a new client. So why do I see so many “professional” people airing their dirty laundry on Facebook, sharing their extreme views on Twitter or ruining their hopes of promotion with their Instagram feed? Everything that you post on the Internet is there to stay and that means that employers, clients and suppliers can see it. Don’t post anything that could come back to haunt you.

#9 – Missing or Incorrect details on Marketing Pieces

Perhaps the most embarrassing error of all is making the decision to invest in a piece of marketing to encourage customers to contact you and failing to include the correct contact details. I’ve seen newspaper ads requesting a call without giving a phone number, large-format ads with misspelled web addresses and direct mail invitations that don’t include the address they hope you’ll visit. Check that your communication includes all the information your recipient needs to do what you’d like them to do.