Stop limit orders are really only useful when selling coins. They allow us to set a condition: we specify a price, and if the price becomes less than or equal to that price, a market order is automatically placed for us. The advantage here is that if we need to step away and will not be able to watch the price, we have some protection if the market begins to plummet. The disadvantage is that we are counting on there being good buy orders available to fulfill our sells. If a massive amount of market sell orders were to be executed right before your stop is triggered, it’s technically possible to be left with the bottom of the barrel. This has happened before, but is not common.
Always pay attention to Bitcoin. Most altcoins (every cryptocurrency except Bitcoin) are pegged more closely to Bitcoin than Asian currencies were to the USD during the Asian Financial Crisis. If Bitcoin price pump drastically, altcoins price can go down as people try to exit altcoins to ride the BTC profits; inversely, if Bitcoin prices dump drastically, altcoin prices can go down, too, as people exit altcoins to exchange back into fiat. The best times for altcoin growth appear when Bitcoin shows organic growth or decline, or remains stagnant in price.