Talk the talk
Becoming well-informed with industry abbreviations and vocabulary is challenging enough. However, you need to also consider that each company commonly uses their own vocabulary when communicating internally. As you increase your involvement on a project, make sure to ask what something means or to clarify your understanding. The more you can adopt their vocabulary when communicating with the customer, the more comfortable they'll be. For example, if your customer uses the word client to describe their service consumer, but you keep using the word account, it might lead to increased time being spent on your customer correcting you or your communications. Effective teams will have a list of common customer vocabulary so that new consultants can quickly get up to date on their communications.
You might work on projects that cross multiple countries and languages. Be aware of differences in how words are used. For example, you might say that you're going on vacation, whereas your customer might say that they're going on holiday. More importantly, some terms can be overloaded. For example, consider a scenario where you ask the customer: "How is your turnover?" The customer might reply that their turnover is increasing rapidly. While you implied their employee rate of leaving, they replied about their revenue. When communicating, you can add extra clarifying information to ensure that your communications are clearly interpreted. For example, in this same scenario, you might have asked, "How is your employee turnover?" As a result, you might have received a different answer, but maybe the one that you wanted.
Different cultures and countries have different standards for what's considered offensive or inappropriate. Often, people use expressions and sayings in communications by habit without considering the audience. As you enter a project, take time to familiarize yourself with what might be appropriate and inappropriate. When in doubt, avoid colloquialisms.