It all depends on individuals because some guys are ready to take a more riks based on their financial background. People should know these investments are very risky so you should start with the money which you're ready to lose. For some people, it may be $10 and for some people, it may be $1000 or even more.
Trading is not so easy just by watching some youtube videos you can multiply your money 10X.
There are many experts itself lost a lot of money in trading so at the beginning start with more stable coins like bitcoin and slowly move to other good altcoins. Money making is not easy but needs to put hard work to earn.