It takes a lot of courage to invest, especially if you are looking for big gains because big gains mean big risks. There are always good times to invest, but if you are a beginner, you might want to avoid this first method and go for the second.
Method 1
This can be risky and often you don't have much time to react. Here you must wait for the market to go into a downwards spiral, where investors get scared and sell stock without very many investors buying. As stock prices get cheaper, wait for the market to stabilise for a while then buy. Hopefully you managed to buy at the bottommost point, as the prices will soon rise as investor confidence returns.
Unfortunately, the market may steady, only to keep falling so you may lose money. If this happens, hold onto your stock as the market should eventually rise and you will probably end up making some money in the long run, although not as much as if you had brought at the bottom prices.
Method 2
This is pretty straightforward.
Do some research and find a company that has a good record with good positive gains per annum. Invest in the company and wait. That's all really. Expect smaller gains unless you find a cheap company that is expected to grow fast. This is more risky of course.
Investing is a fine art, except to make some money but be prepared to lose some. Good luck present and future investors!