Art dealing can be a tricky business. Insiders share the ins and outs of their 'unusual' world

Art dealing often requires contacts — and the ability to take risks.

Mark Lambert has bought and sold works of art by the likes of Andy Warhol, Pablo Picasso and Claude Monet during his more than two-decade career as an art dealer, an occupation he got into almost by accident.

After a degree in fine art, Lambert imagined he would become an art teacher, but a chance meeting with an art dealer who hired him as an assistant set him on a different path. "I started as the framer and the tea boy …  and I stayed there for 17 years," he told CNBC by phone.

He specialized in 19^th century Victorian paintings at the time, and would exhibit at around 20 international art and antiques fairs each year. Then, after a stint at another dealership, he opened his own gallery in September — Lambert Fine Art — in the British town of Stratford-upon-Avon.

Dealing in art is a trade Lambert described as "unusual," because art is often a purchase driven by emotion rather than need. "You don't need it. You don't have to have it. People want it, they aspire to it. From that regard, I suppose it's unusual. And I think most most people that buy art are investing in something for themselves ... they want to look at it and enjoy it every day," Lambert said.

Selling art via a dealer rather than at an auction can also help pieces maintain their value, Lambert said — if a picture doesn't achieve its low estimate at a public sale, it can reduce its perceived value and lessen demand. "You can 'burn' a picture by putting it to auction sometimes, if it doesn't sell properly or sell well," Lambert said.

The world of art dealing can be intimidating to new entrants, according to Olya Johnson, an interior architect and co-founder of art and interiors business Relic,