Normally in trading, a smaller investment provide smaller return and when the investment amount is more, the return will also be greater. In this case, risk is an important issue. Trader should understand well how much he will invest and how much risk he will accept. In terms of avoiding risk, if a trader does not invest all his total assets at once, but wants to divide his investment into small parts, it is also not a bad idea. Some traders want to earn more profit in a short time, while others want to be satisfied with a small profit with a small risk. Everything will depend on the investors himself.
The decision of the trader will depend on how guaranteed he thinks the investment is because for an investment that you don't have any certainty of what's going to happen, you can't be risking big amounts for the trades. Big amounts should only be risks for trade that you have done different analysis on and you're certain you won't lose. Losing shouldn't be because you didn't do your analysis right but because the market changed from under circumstances that you had no control over. Traders are always advice to use small amounts but many of them refuse to listen to this advice and this make them to constantly lose. Big amount should only be introduced after you have perfected trading that you can hardly lose.