I want to aim this mostly at the newbie traders. Those who've been flirting with the idea of trading for ages. Maybe you've tried your hand at it but failed or perhaps you haven't dipped your toe into the water as yet.
Trading is not hard, the psychology is hard, but there are ways to deal with that.
First find a strategy you think makes sense, then start working on it. Test it with hundreds of back tested paper trades. Tweak as required and test again, rinse and repeat until you have something that seems to have a profitable edge. This may take you weeks of manual work - that's fine.
Then when you have something that seems to work, start with a small amount of money. Small as this will help reduce the stress.
Set the rules and risk management and get trading. Track your performance, your perfect trades and keep a journal. Importantly change NOTHING about the system. Ideally you should trade the exact same system for the entire 2018. If it is losing money badly, then your testing was bad. But by the end of 2018 you'll ideally have a working trading strategy and you can start increasing the portfolio size.
Point is start and have modest expectations. Aim to break even in year one - that's winning.