Investing is risky for amateurs. You need to seriously educate yourself before you invest. If you don't know what a market beta, P/E ratio, P/B ratio, dividend yield, dividend cover, EPS, ROCE is, you really shouldn't be investing.
2 things to invest successfully:
1) Buy a great company. Do some digging. Read the balance sheet, look at the P/E, look at the dividend cover etc. See how it is doing on the high street. Have they got any contracts down the line etc?
2) Buy at a great price. Look at chart technicals. Buy when the stock is selling below intrinsic value. No point overpaying for a great company, you will go years without making profit. Look at ABF (listed on LSE) as a good example, 2 years of zero gains, even though primark is a great company. This happened because the stock was on a high P/E and had to correct if primark didn't keep over delivering on profits.
Now achieving both 1) and 2) together can be hard, but if you do, trust me you will become rich. Even if you can achieve 1) or 2) , you will make money. But it's always better to have 1) over 2) in the very long run. A great company will outperform a poor company over decades.
"Time is the friend of the wonderful company. The enemy of the poor" Warren Buffett