My biggest mistake in trading

I first started my trading about 2 years ago. I tried to attend as many investment talks as I could and hope to gain tips on what stocks I should invest in. My biggest mistake was to believe fully what these investment 'experts' said and blindly invested in the stock market. I had lost about 80% of my invested funds and did not know how to set the target to cut my losses. I have since gain experiences and be more cautious in my investment journey.