Most of these services offer some form of free portfolio tracking - this enables you to create a portfolio and track it properly to see how you do with no money on the line. This used to be known as paper trading in the 'good old days' before 2001. This kind of exercise can be a good way to learn and play around with things without being either serious or costly.

Before making your first investment, take the time to learn the basics about the stock market and the individual securities composing the market. There is an old adage: It is not a stock market, but a market of stocks. Unless you are purchasing an exchange traded fund (ETF), your focus will be upon individual securities, rather than the market as a whole. There are few times when every stock moves in the same direction; even when the averages fall by 100 points or more, the securities of some companies will go higher in price.

Benjamin Graham, who is known as the father of value investing, has preached that the real money in investing will have to be made—as most of it has been in the past—not out of buying and selling, but out of owning and holding securities, receiving interest and dividends, and benefiting from their long-term increase in value. This practice has created millionaires.
On when to buy, my recommendation is to avoid jumping into the pump train when you see a cryptocurrency price rising very fast. Fear of missing out is a very potent psychological trigger for us humans and if you see something rising fast the first thing you’ll want to do is buy some so that you don’t feel left out. Go for the dip, but go for the dip reasonably: identify the cryptocurrencies you want to own, ideally solid ones based on your own research (it’s important not to invest in crappy projects), and when you see them taking the plunge go grab some big chunks.
Fear of missing out: the psychological concept of buying something because of the fear that we may miss out on hypothetical future earnings, or that the occasion is too good and might not present itself again. Abbreviated FOMO, this is typical of very huge sales/discounts, such as Black Friday, where people buy a lot of useless stuff because they fear they may miss out on a huge bargain. FOMO is very much linked with « pump and dump » movements.

The exchange may offer privileged services like high-frequency trading to larger clients like mutual funds and asset management companies (AMC), and earn money accordingly. There are provisions for regulatory fee and registration fee for different profiles of market participants, like the market maker and broker, which form other sources of income for the stock exchanges.

This is a more advanced topic for those who want to do what is called « day trading », i.e. those who plan to buy and sell on a daily basis as their main activity. Arbitraging is the process of leveraging price differences between exchanges to make a profit, by buying cryptocurrency cheap on a given exchange and selling it for a higher price on a different exchange.
The biggest obstacle to stock market profits is an inability to control one’s emotions and make logical decisions. In the short-term, the prices of companies reflect the combined emotions of the entire investment community. When a majority of investors are worried about a company, its stock price is likely to decline; when a majority feel positive about the company’s future, its stock price tends to rise.

Buy “the basket”: Can’t decide which of the companies in a particular industry will be the long-term winner? Buy ’em all! Buying a basket of stocks takes the pressure off picking “the one.” Having a stake in all the players that pass muster in your analysis means you won’t miss out if one takes off, and you can use gains from that winner to offset any losses. This strategy will also help you identify which company is “the one” so you can double down on your position if desired.