If you plan to buy or sell cryptocurrencies through a trader, choose one that has an very good rating and consider using the peer-to-peer exchange where the conversions are carried out using escrow. During the conversion, the third-party custodian is in charge of meeting the agreed terms. If the conditions are met, the funds will be exchanged. Otherwise, they will return.
Avoid exchange at a personal meeting. Such an exchange is very risky unless it is a counterpart you fully trust.