There is no required amount to start trading, so decision is yours. Never spend more than you can lose without unpleasant consequences. Then there won’t be a reason to worry about. You will easily go through the ups and downs of the market with an opportunity to buy more coins. In spite of apparent simplicity, it’s easy to get lost. But don’t panic. Only a cold math and detailed plan are your friends. So It’s better to care about your trading skills, than about the amount.