I start trading from about 0.005 BTC, it was because I was totally new to trade, and I want to invest a lowest amount so that I will not lose any bigger amount, after that I remained successful and I increased my amount of trade , so I continued in this way like increasing my amount of trade and at the same time I continued to learn.
Yeah , better to learn from ground and up from time and time also you can learn about trading events . I think 0.005 is good start for trading also you can get decent profit if you choose right coin , and still has a chance for being lose if you choose shit and wrong coin .