If you don't simply sell products you must be selling a service or service with a product.
Everyone has knowledge to give away to show they know what they're talking about and that is great marketing.
Today I 'nipped down' from Manchester to Milton Keynes to do a no-fee 1.5 hour presentaion to a group of business development team of people who run and manage conference centres.
Why did I give up approximately 8 hours for free?
To market my expertise. These people will have some clients looking for speakers. The presentation seemed to go well and at the end my contact offered to promote my training and presentation skills.
In most areas...THE MORE YOU TELL, THE MORE YOU SELL
But make it useful, valuable and practical