To sell a service versus to sell a product or both

I have been unsuccessful in getting clients on the freelance site UPWORK.com.  The clients seem to be very picky and have overlooked me for other artists.  I am not sure if I  want to continue trying to "sell a service." 

I plan to focus on selling my products.  Getting my name out there as an artist and writer.  I use amazon to sell my books so I plan to continue pushing my books thru them.