An early start in investing can be a huge advantage, but investors must quickly learn to make the most of opportunities. Thinking like a small-business owner can yield great benefits to investors’ portfolios. Running a small business means selling goods you know inside and out to customers you know equally well: what they like, what they buy, what they reject. Using a similar mindset, novice investors can manage their portfolios by understanding what works, controlling risk, and building knowledge. It’s about knowing the details of what is in their portfolio and how each stock, and the company behind it, operates. Columnist Andrew Allentuck and financial planner Benoit Poliquin give new investors a much-needed introduction to the critical skills that will maximize their investments’ values over their lifetimes.