Particularly in work settings, if you have concerns that there may be different recollections about an in-person conversation or phone call (e.g. during a vendor negotiation or a discussion regarding expectations of deliverables), create a paper trail of the conversation to ensure that there's a common understanding. While it can feel awkward to send a follow-up email recapping what you talked about, it's a good habit to get into. And eventually, it'll start to feel normal.
The email may be as short as a couple sentences. Just be sure it covers everything that was agreed upon. At the same time, as any lawyer will tell you, it's important to be conscious of what you put in writing because it could be used against you in the future. So, use good judgment about what you choose to have "on the record".