It's a small amount, so investing is not an option. I recommend to just create an encrypted paper wallet and forget about it.
Yes it is good idea that way invest our bitcoin and make it smart strategy because we are a type of cyrptocurrency that volatile movement.In terms of buying bitcoin make sure that the value was decreasing so that you have many ways to buy it.Then if time that the value of bitcoin will pump up this is a right time to sell it.A simple strategy but big income if you have an effort to so it.
Yes,that is the strategy,buying the dip and selling high.I think of that took,but we can hardly tell which direction the market will turn in the next 24 hours.Sometimes all the technical analysis we do will just go the winds when there is a FUD in the market,Asian festivities or some government crackdown.things will eventually get better as bitcoin gain more adoption.For now,we do our market research,keep our eyes and ears wide open and wait for any news that may have positive or negative impact on our cash and make our decisions accordingly.Trade your 20$ bitcoin smartly.Good luck.