For short period of time you do not need to focus on the top coin in the market because those are coin good to hold for long period of time, good coin for short term is they are having small amount of value which is very actively fluctuates and take that advantage to make good income.

But i suggest that you need to have fund for short term and for long term trading to lessen the risk of your money because you will have an option if you fail in short term you have reserve fund for long term to get back you loose capital.