On Wednesday, the US Securities and Exchange Commission agreed on a proposal for groundbreaking rules that would allow almost anyone to buy shares of stock in start-up companies.The rules, if approved after a three-month comment period and review, will mean crowdfunding portals can open up to the general public. And, to concerned investor advocates, it also means a whole new set of investment pitfalls and potential frauds to watch out for.But the United States isn’t the first country to tiptoe into start-up investing free-for-all, and Americans have much to learn from recent forays into crowdfunding abroad.