A good rule to follow is never to invest more than what you would be willing to lose.
Its not only good, its the golden rule for any investment. Without being greedy always ask this question to yourself, how much we can afford of losing!!!
I used to trade in forex and Bitcoin is not exceptional of it. When we think the price is at lowest, now is the best time to buy it may show a sudden drop. Recently Mark Carney, Bank of England governor and head of the Financial Stability Board told to G20 members that crypto assets do not pose risks to the worlds economy. I cant believe how there is sudden rise in BTC price.