Whether for a sales call, presentation or negotiation, business professionals should look their best when visiting a client. Some industries may require formal attire for a client visit, but for many business casual clothing is preferred. Remember, you should always at least be as dressed as your client, but being dressed too formally in comparison can have unintended consequences of making the client feel uncomfortable.
A nice pair of dark wool pants accompanied by a long-sleeve button-down dress shirt and black leather shoes is appropriate for an initial client meeting or a meeting with a client in a more formal industry. Khakis and lighter colors may be worn on subsequent visits as long as the client has a similar dress code.
Before going, figure out what the client's dress code is and dress a bit nicer
Remember not to dress too formally compared with the client - it can make them uncomfortable
Call ahead to figure out what the clients dress code is