What are some of the most important things for young, first time entrepreneurs to know?

Just three things:

1. Develop the worst case scenario. How could it go wrong in the absolutely worst possible way? Most people reply to this by saying "That's easy, I don't sell anything". And I point out that that isn't the worst thing. Worse by far is being sued by a customer because the thing you sold caused an injury or death. Worse still is if the manufacturing process injures you? Is loss of your health possible? Whatever the worst case scenario is, find out and then ask yourself "Could I survive that?" If the answer is yes then go ahead. If the answer is no then walk away and find a less dangerous business idea. Ideas are cheap so you can always find a better one.

2 A great piece of advice from James Alltucher: always produce a product even when you offer a service. That way, if it all goes belly-up, at least you still have something to show for your time. And if it doesn't go belly-up, a product is a great way to scale up the business without working yourself into the ground. Boy, I wish someone had told me that 30 years ago.

3 Develop an exit strategy. This is not planning to fail. It's a way of recognising that the project is failing so you can get out before it ruins you. Set an absolute limit on one thing. It can be the amount of money you will borrow or the amount of time you will give. It doesn't matter what it is, it only matters that it exists. If you ever hit that limit, you know things are failing and, at that point, you can then decide to press on or walk away. If you press on, at least you now know that there's a problem. Boy, I wish someone had told me that 30 years ago as well.