Long term=I don't venture out top 100 normally (unless a super promising project with rep) Ex ETH or BTC right now.
Short term=Anything that has value and that upcoming roadmap something is happening. Ex ETC right now.
Short is dont to short and long is dont too long, that is the way i do it.
I never do very short trading like 1 day or 2 days and i never did trading more than 6 months. This way i do because i think this is smarter when we can make round trade and gain more money but not very short because its very risky
sometimes, doing middle trading is a good decision if the coin doesn't give a good progress to increase and sometimes this type of coin is not getting high in short-term. like a cheap coin which does not increase higher in the short-term, we need to hold for at least 1 month after we buy so we can see the price is increase although it is not significant.