be a wise investor only happen with so many tries and failures, even big investors do mistakes but they know they can make it up and know how to move on, there are so many books about trading and investing but still, nothing would replace experience , and an experienced investor has lost so much money to be expert, everything has a price and nature doesn't give it to you until you pay the price for it, so if you think you can tolerate losses and heavy losses then you should be good, profit comes with risk and you can only expect big profit where there is a big risk...
Absolutely, in life, you are not always winning sometimes you fail but that doesn't you are a failure because more failure you've experienced the more knowledge that you can gain. But it is better for you to be intelligent of what you are doing especially when you are invwsting because your money is involved, so to avoid failure you need to study and understand what you need to understand.