There is no minimum level to start trading with the crypto market. But I think that at the beginning you should not invest too much because you have a very high failure rate because of this new market. 0.1 btc is a reasonable amount.
i think 0.1 Bitcoin is too much for beginner. it should start by smaller amount again in around 0.02-0.05 Bitcoin is more than enough for beginner. and some exchange also apply minimum deposit but 0.05 bitcoin is enough.