As an experienced trader (but not professional ) i will give you some advices on how to trade successfully and less risk
1. Learn trading basics first like Watching tutorials on youtube, Reading threads here on trading discussions, Reading bitcoin trading blogs and etc.
2. Look for good coins and check their backgrounds if they have a good projects, Better to choose coins that are on top 50 in Coinmarketcap.
3. Do not invest all of your capitals on 1 coin only spread your capitals about 5 - 10 coins depends on how much your capital, Investing all of your funds on 1 coin only are very risky unlike investing on many legitimate coins you'll become much safer.
4. Don't be greedy, Greed will result to lose if you think that your profit are enough go close that position to expect too much earnings and if your coin goes dump patience is the key to become successful don't do panic selling.
5. Try to learn chart reading it helps you alot with your trades because you can read the market movement.