If we had such a thing, this would surely be one of ETR’s 10 Commandment’s of Start-Up Businesses: Make sure your product will sell before you do anything else!

But when I recently caught a few moments of Tori Spelling’s “Watch me start a new business every week” reality show, it was obvious she doesn’t know this rule.

Tori, you see, wants to create a business that’s all about French fries. She wants to make “chic, gourmet fries” and sell them with a selection of unique dipping sauces.

On the episode I watched, Tori and her husband Dean were looking at mock-ups of fry cones – paper holders with fun decorations on them. Turns out, Tori prefers a red and turquoise design to any of the colors her friend? business partner? fry-cone designer? brought for her to look at.

After the meeting, Tori revealed that they “have yet to buy a single potato.”

Talk about putting the cart before the horse. Those fancy fry cones aren’t going to matter a lick until Tori finds out if people will actually buy her fries.

You may be excited about your new business. But as Michael Masterson has said so many times before, don’t go overboard buying business cards, office stationery, a new desk chair, or anything else that’s not necessary to getting the product sold. Instead, spend your time and money on finding out whether people will buy the product. Test it – at a farmer’s market, a street fair, via PPC ads online, or anywhere else you can. Everything else is unimportant.

[Ed. Note: If you need step-by-step advice about what to do – and when to do it – when it comes to starting a business, pick up Michael Masterson’s New York Times, Wall Street Journal, and BusinessWeek best-seller Ready, Fire, Aim. It will show you everything you need to do to start a business and grow it to $10 million, $100 million, and beyond.]