"Do what you love and the money will come." It's a phrase more than one well-meaning family friend has murmured to me. Little did they know that as a cynical millennial, I don't believe that. Or at least, I didn't.

Because the older I get, the more I realise that what you do for a paycheck isn't the only route to passion. Your hobbies don't just have to be for fun. They can also grow into valuable investments. Here's how.

Graphic novels, that is. In a passionate bid to ensure I didn't have a proper girlfriend until well into my late teens, I read Donald Duck comics throughout school. Heck, I still read them! Over the years I spent many a week's pocket money on the books, but my pride and joy remains half a dozen old packing cases. Why? Because inside them are titles dating back to the 1960s, given to me by a family member and fellow comic nerd.

I still have those boxes packed away somewhere, and you'll forgive me for thinking of them as potential goldmines. These comics can fetch big bucks — in 2008, the first Swedish edition of Donald Duck, a 1948 issue, sold for a tidy US$16,600. So have a rummage around your own old comic books or toys — you never know.

Tip: Even if you collect old books for enjoyment and not investment, store them wisely so they don't perish. You don't want to find out two decades from now that your first edition of The Art of Charlie Chan Hock Chye would be worth thousands — if only it weren't for the water damage.

Forgive my "timekeeping" pun, but watches are so hot right now. Singapore even publishes 24-7, an entire magazine dedicated to female watch connoisseurs. But watches aren't just about being catwalk-fabulous and looking bling. They're also a popular investment.

As a Wall Street journal article notes, "A sought-after Rolex with the proper paperwork can be taken to any major city in Russia, South America, Indian and now China and turned directly into cash," says Edward Faber, a watch dealer with New York's Aaron Faber Gallery. The article also advises that if you want to start a collection, it's wise to go deep. Focus on one brand, and snap up models within their family to grow a strong, holistic "set". Rolex and Patek Philippe are good bets.

Tip: Ask if your parents or grandparents have any old watches lying around. You might be surprised at the number of potentially valuable pieces that turn up that have passed down through multiple generations.

Do you know any people who've taken up art for a living? Take an interest in their work. Not only will bonding over their pieces keep you closer, they may also be able to give you a flavour of the art scene at the moment. Armed with this info, you'll get an insight into types of art you can invest in.

And if you can't get enough of your friend's art, why not start by buying from them? It might sound silly, but buying some pieces from acquaintances now could be the best investment you ever make.

You don't want to end up like British comic actor Brian Blessed, who as a young boy in the 1950s met Pablo Picasso. "If you're really Picasso, draw me something," Blessed said. Picasso duly obliged with a sketch of a dove of peace, but young Brian wasn't impressed.

"I threw the drawing to the floor and in doing so, threw away about 50 million pounds," he recalled in a recent interview. The sketch was picked up and now hangs in Britain's Sheffield Gallery.

These specific hobbies don't have to become your own — you might be more of a fan of first-edition film posters, fine wines or action figures.

Whatever your passion project, you'll find thinking of them as investments is a great way to enter the world of "real" investments like stocks.

As you grow your collection you'll learn about appreciation, diversifying, trading and protecting your "portfolio" — all valuable skills. Now if you'll excuse me, I'm bidding on a 1971 Donald Duck comic on eBay right now!

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