You need to have atleast 0.1 Btc as per my understanding to start actually trading and get some small returns to it . You can trade Btc with some new altocoin and exchange back to Btc again with some gains for holding for some days .
i think we can even start trading from less that 0.1 bitcoin.
Correct, you can even do it from 0.05 Bitcoin like I do. Just choose stable coins and when the profit is coming up you can sell your coins to get the profit or if you were a risk taker you could try it with new coins.