There is no constant amount mate of how much you can use to get your started. However, I would tell you to not invest too much, especially if you're just starting with your ventures.
Sure, at the beginning, it's hard for you, but if you try to read and understand and ask questions then you will definitely catch up on the trend. How much money to invest is not as important as the knowledge you need to be able to succeed in this market so equip yourself with a wealth of cryptocurrency knowledge before making an investment decision.
We need to trade with less valuable coins in case of short term while trading with more valuable coins is of long term. Furthermore check your savings which may allow you to trade with either valuable coins or less valuable coins. Both are benefited for you if you trade with either Bitcoin or Altcoin but would need more struggle in collecting profit from Altcoin. However one can get huge profit from the Bitcoin after a long term trading.