If one is a consultant or an independent (on one's own), marketing oneself or one's services is a necessity. However, one doesn't necessarily need a class or course. A lot of marketing is just common sense.
One should understand and appreciate customer relations, of which a key element is to listen to the customer rather than blathering, promoting, or preaching. Of course, once a rapport is established, then small talk is part of the interaction.
I learned marketing by doing and following the example of a company VPres/Pres, who made it a point to talk to clients and potential clients on a regular basis. With that approach, we'd keep up with the 'market' and be aware of potential projects.
Another part of marketing is being able to ask the right questions when presented with a technical problem, and that is where experience comes in.